[Guide] How To Setup And Use Fastboot

What, If Any Other Tutorials Would You Like Me To Make?

  • Tutorial on setting up and using ADB

    Votes: 434 51.5%
  • Creating flashable .zips to be used in recovery

    Votes: 486 57.7%
  • Whatever I want!

    Votes: 195 23.1%
  • Nothing! I make terrible useless guides!

    Votes: 34 4.0%

  • Total voters
    843
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trevor7428

Senior Member
Feb 10, 2012
341
99
Las Vegas, NV
Ooops, good catch! Yeah it should read .img
Just fixed it

Sent from my Nexus 4 using Tapatalk 2

Lol I was thinking, I don't know much about this stuff. But there's no way that can be right.

I read the whole thing. Thanks I learned alot. And will see if some stuff will work on my Asus tf300t. I know some commands are a lil different, but same concept.
 

villan.co

Senior Member
Jun 27, 2013
312
92
villan.me
So plug your phone into PC via usb, have it in fastboot mode (from within bootloader) and open a new terminal, type: fastboot devices
thats the one part i don't know HOW to do - is that phone specific, or is there a general method for that??? thanks. i used "adb reboot-bootloader", but it just rebooted. it MAY be phone-specific, and these LG-L9s seem to be pretty locked down... so, if that's the case, disregard my question (i'm a noob).
 
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demkantor

Inactive Recognized Contributor
Nov 10, 2011
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Everyone was a noob once :D so no worries! Asking questions is what helps one move on
Any how, not all devices/bootloaders support fastboot. I've only used two lg phones in the past, a g2x which didn't support fastboot and a nexus 4 which does, but that may just be that its a nexus but hopefully lg has moved on to the point that their bootloaders do
The command should be
adb reboot bootloader
No - in between (in fastboot mode you need the - FYI)
But to get there manually is device specific, often holden volume down when powering on gets you there
If nothing works for you I would suggest checking your device forum on xda, I'm sure someone there can give you an appropriate answer
Happy flashing!

Sent from my Nexus 4 using Tapatalk 2
 
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trevor7428

Senior Member
Feb 10, 2012
341
99
Las Vegas, NV
thats the one part i don't know HOW to do - is that phone specific, or is there a general method for that??? thanks. i used "adb reboot-bootloader", but it just rebooted. it MAY be phone-specific, and these LG-L9s seem to be pretty locked down... so, if that's the case, disregard my question (i'm a noob).

Ya I'm not sure if LG phones use fastboot or not. If you go to ur device specific thread on xda. Fastboot should be mentioned somewhere noticibly. If so, every phone tablet I've used to get to fastboot mode hold power + volume down. Then if there is fastboot there should be text. Saying ex. Press volume down thento scroll to fastboot ( USB symbol) volume up to select. It won't exactly say that just something like that.

Once fastboot is selected, then go to comp. Phone should already be plugged in. Open command prop and type fastboot devices. Assuming you have set up adb and fastboot as said in OP
 

Russell_

Member
Aug 22, 2013
39
6
Firstly, demkantor, I've clicked on the Thanks button for a great post!

Now my question. I understand how you can use fastboot to "flash" different partitions.

e.g., fastboot flash recovery some_recovery_version_x.img

will change your "recovery" partition to the one you've specified.

And, if you only temporarily want to use a recovery and not flash the partition you can issue:

fastboot boot some_recovery_version_x.img

If you're having problems, as long as you can get into fastboot mode you're "safe" as you can always flash various partitions. As I begin experimenting I'm naturally concerned about bricking the phone and am struggling with the connection between the bootloader and fastboot. Is fastboot part of the bootloader? That would imply that I need to be extra careful about the bootloader partition (is that "boot"?). If it's part of the bootloader and "boot" is the partition name does than mean if one does:

fastboot erase boot

followed by

fastboot reboot-bootloader

one now has a brick since the first command has erased your boot partition?
 
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trevor7428

Senior Member
Feb 10, 2012
341
99
Las Vegas, NV
Firstly, demkantor, I've clicked on the Thanks button for a great post!

Now my question. I understand how you can use fastboot to "flash" different partitions.

e.g., fastboot flash recovery some_recovery_version_x.img

will change your "recovery" partition to the one you've specified.

And, if you only temporarily want to use a recovery and not flash the partition you can issue:

fastboot boot some_recovery_version_x.img

If you're having problems, as long as you can get into fastboot mode you're "safe" as you can always flash various partitions. As I begin experimenting I'm naturally concerned about bricking the phone and am struggling with the connection between the bootloader and fastboot. Is fastboot part of the bootloader? That would imply that I need to be extra careful about the bootloader partition (is that "boot"?). If it's part of the bootloader and "boot" is the partition name does than mean if one does:

fastboot erase boot

followed by
,
fastboot reboot-bootloader

one now has a brick since the first command has erased your boot partition?

Depending on what device. You may or may or may not be able to wipe boot.img. if you are able to wipe the bootloader. You would want to flash. A new boot.img right after while still in fastboot mode. If not, you would be bricked. I'm not sure about hard brick, but def. Soft bricked. The OP would have to clarify on that one
 

demkantor

Inactive Recognized Contributor
Nov 10, 2011
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mpls
Boot.img is you kernel, the command fastboot boot xxx.img just temp runs that image as a kernel (in a sense) so it will boot whatever your telling it.
So you can take a recovery.img and just boot it temporarily but the reasons to do so are limited and once you reboot normally it will boot to os or your installed recovery
So no, fastboot erase boot will not erase your bootloader. And actually the command fastboot erase bootloader or hboot or radio - none of these are true commands, you can only overwrite these partitions and never erase or format them (at least not with fastboot)
But be careful when flashing either a radio or bootloader, be sure to make sure its for your device and the md5sum matches or you could end with a brick. But fastboot is by far the safest way to flash as you will get a return of an error if something went wrong.
Oh and fastboot is not really part of your bootloader, its an executable program that interacts with a bootloader. It is like adb in this sense. But all ROMs have adb abilities while not all bootloaders will interact with fastboot, and the ones that do may have limited options avalible

Sent from my Nexus 4 using Tapatalk 2
 

Russell_

Member
Aug 22, 2013
39
6
Boot.img is you kernel, the command fastboot boot xxx.img just temp runs that image as a kernel (in a sense) so it will boot whatever your telling it.
So you can take a recovery.img and just boot it temporarily but the reasons to do so are limited and once you reboot normally it will boot to os or your installed recovery
So no, fastboot erase boot will not erase your bootloader. And actually the command fastboot erase bootloader or hboot or radio - none of these are true commands, you can only overwrite these partitions and never erase or format them (at least not with fastboot)
But be careful when flashing either a radio or bootloader, be sure to make sure its for your device and the md5sum matches or you could end with a brick. But fastboot is by far the safest way to flash as you will get a return of an error if something went wrong.
Oh and fastboot is not really part of your bootloader, its an executable program that interacts with a bootloader. It is like adb in this sense. But all ROMs have adb abilities while not all bootloaders will interact with fastboot, and the ones that do may have limited options avalible

Sent from my Nexus 4 using Tapatalk 2

Thanks for the reply.

I do understand the part where you can temporarily boot an image using "fastboot boot x.img". I recently did that is because I didn't want to move away from the stock recovery but wanted root access ... so I booted temporarily into ClockworkMod's recovery and installed Chainfire's SU zip. I think that is a valid reason to want to do it. I guess another may be to make a backup (since the stock recovery does not let you do it)? I'm a newbie trying to understand stuff before I do and I do appreciate you taking the time to explain.

I do realize that fastboot and adb are commands executed on the computer you connect (e.g. Linux, PC) to interact with your connected Android phone and that (for those devices that support fastboot) there is a fastboot driver and an adb driver that needs to be installed (if you're on a Windows box). But the device itself can be powered down and then powered up (by pressing volume down) into fastboot mode. Doesn't this mean that fastboot is code which gets loaded from some partition? Or is it like the BIOS on a PC which has it's own flash memory? Does this mean that if you're in fastboot mode (for those devices that support fastboot) that the bootloader is yet to begin executing? So in fastboot mode if you select "Recovery" it turns controls over to the bootloader to load from the recovery partition and the phone now is in recovery.

I'm still intrigued about flashing a wrong radio causing your phone to be bricked ... but I'd like to understand what I describe in the above paragraph first.
 

demkantor

Inactive Recognized Contributor
Nov 10, 2011
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@Russell_

I may have used bios as an analogy but its not the same, and it isn't a separate partition like on a PC. Fastboot mode is part of your bootloader, your bootloader has several parts and functions and you'll often find sbl1 and sbl2 etc. Even as separate partitions
When you initially get into fastboot mode you have started you bootloader and stopped it before it booted to a partition such as recovery or the os, you haven't even started the android kernel to run yet.
The reason why flashing a bad or incompatible radio can brick your phone varies a bit on devices, it depends on how the radio functions and how your bootloader functions. On some devices your baseband/radio/modem/whatever won't stop your phone from booting. The way many bootloaders interact with the radio can.
So when the phone begins the boot process it runs checks against the radio for security flags/compatibility etc, if there is no radio present or an incompatible one it will just not start and you will need JTAG to fix it
Sorry if I'm not fully clear, a bit tired this morning but feel free to ask and all try to explain better :p

Sent from my Nexus 4 using Tapatalk 2
 
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OMJ

Recognized Developer / Inactive RC
Jun 11, 2007
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Great guide! with more phones coming w/ no storage card (HTC One) I've seen many ppl make the mistake of accidentally erasing their internal storage leaving them stuck trying to sideload a ROM to flash....I've never flashed a ROM via fastboot, but it's good to know how :)

btw...I didn't see the cmd u used to list the partitions, I've seen "$ cat /proc/emmc" for linux, is there a windows cmd?

thx
 
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hp420

Senior Member
Jul 31, 2011
2,591
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Gainesville, Fl
Google Nexus 4
T-Mobile LG G2
the section covering the splash.img flashing is great, thanks! in my personal experience, these are only available for htc devices. can i use the information here to change a nexus splash.img? as much as i'm a huge google fanboy i've been dying to flash a new one and get rid of the plain boring google logo.
 
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demkantor

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Nov 10, 2011
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@O.M.J
Sorry, haven't finished editing that section, flashing a splash is fairly device specific so I was trying to find a way to incorporate how fastboot does it with phones that have this option.
Anyway the commands are the same for linux as on windows, what I mean is that you are executing commands through a shell (in cmd but adb shell) which is running Linux, well android, but for the most part all your commands are the same/similar. you can ls, chmod, mkdir, cat, etc
I'll add a few quick tips in that section but im trying to keep this more on the fastboot end of things rather than adb


@hp420
Yeah mostly HTC devices, so nexus one, just not nexus 4
actually I think you can with a galaxy nexus as well, just not through fastboot, I believe a bunch of the galaxy phones store the splash in paramfs and you just use a hex editor to allow for the change.
And also many Motorola phones have an option to, in fastboot it is like
Code:
fastboot flash logo.bin logo.bin
and some Sony's have an option as well, but i believe its in the kernel/ramdisk or something.
Like i said above, i need to finish editing that section to make things more clear!
@matt95
A little off topic is always cool, no worries!
I love that clip too, added it to my HTC vision thread first time i seen it! There's also a few others if you search your tube
 
Last edited:

Mooncalled

Senior Member
Great guide! Helped me out quite a bit the first time I used it. I was able to successfully erase my system, data, boot, cache and recovery. The second time around though I got these messages when I was trying to update to the latest Odyssey build. Not sure why I'm getting "remote: not allowed"

Code:
C:\Android\android-sdk\platform-tools>fastboot devices
HT24LW407872    fastboot

C:\Android\android-sdk\platform-tools>fastboot erase boot
erasing 'boot'...
FAILED (remote: not allowed)
finished. total time: -0.000s

C:\Android\android-sdk\platform-tools>fastboot erase boot
erasing 'boot'...
FAILED (remote: not allowed)
finished. total time: 0.016s

C:\Android\android-sdk\platform-tools>fastboot erase system
erasing 'system'...
FAILED (remote: not allowed)
finished. total time: 0.000s

C:\Android\android-sdk\platform-tools>fastboot devices
HT24LW407872    fastboot

C:\Android\android-sdk\platform-tools>fastboot devices
HT24LW407872    fastboot

C:\Android\android-sdk\platform-tools>fastboot erase boot
erasing 'boot'...
FAILED (remote: not allowed)
finished. total time: 0.000s

C:\Android\android-sdk\platform-tools>fastboot flash boot boot.img
sending 'boot' (5764 KB)...
OKAY [  0.842s]
writing 'boot'...
OKAY [  1.310s]
finished. total time: 2.153s

C:\Android\android-sdk\platform-tools>fastboot erase cache
erasing 'cache'...
OKAY [  0.109s]
finished. total time: 0.109s

C:\Android\android-sdk\platform-tools>fastboot erase system
erasing 'system'...
FAILED (remote: not allowed)
finished. total time: -0.000s

C:\Android\android-sdk\platform-tools>fastboot erase data
erasing 'data'...
FAILED (remote: not allowed)
finished. total time: -0.000s

C:\Android\android-sdk\platform-tools>fastboot erase boot
erasing 'boot'...
FAILED (remote: not allowed)
finished. total time: -0.000s

C:\Android\android-sdk\platform-tools>fastboot flash boot boot.img
sending 'boot' (5764 KB)...
OKAY [  0.842s]
writing 'boot'...
OKAY [  1.310s]
finished. total time: 2.153s

C:\Android\android-sdk\platform-tools>fastboot erase cache
erasing 'cache'...
OKAY [  0.109s]
finished. total time: 0.109s

C:\Android\android-sdk\platform-tools>

HTC One S (TMo) HBoot 2.15.0, TWRP 2.6.3.0
 
Last edited:

demkantor

Inactive Recognized Contributor
Nov 10, 2011
6,861
3,764
mpls
Strange, did your bootloader change recently? It as if you are just unlocked and the commands are limited with out an engineering bootloader. I'm not familiar with your phone so if there is an s-off method or an eng bootloader you can flash then these commands should open up to you again

Sent from my Nexus 4 using XDA Premium 4 mobile app
 

Mooncalled

Senior Member
Strange, did your bootloader change recently? It as if you are just unlocked and the commands are limited with out an engineering bootloader. I'm not familiar with your phone so if there is an s-off method or an eng bootloader you can flash then these commands should open up to you again

The only change I've made is updating my TWRP recovery from 2.5 to 2.6.3. The hboot is the same 2.15.0000. Does superuser permissions play a role in fastboot access?
 

demkantor

Inactive Recognized Contributor
Nov 10, 2011
6,861
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No, superuser, recovery, even root doesn't play a role in the bootloader so this shouldn't matter. Can you write down everything from bootloader screen here?

Sent from my Nexus 4 using XDA Premium 4 mobile app
 

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  • 178
    Introduction:
    I have found that many people are unaware how to use fastboot, which if you have ever owned an HTC phone or something from the Nexus line you know how important it can be.
    About a year ago I got sick of answering questions about fastboot so I made a guide, but it was device specific. Not too bad but I was constantly giving the links to it for other phones... of course more questions just popped up.
    So here i am making a comprehensive yet easy to follow (I hope) guide on how to set up and use fastboot. I will cover the basics for Windows and Liunx (sorry Apple users, just cant stand the product/company)

    I plan to make a series of guides for XDA-University Thus far there is this guide and:
    [Guide] How To Create Recovery Flashable .zips / update.zips

    First a short explanation:
    Fastboot, like ADB, is a tool to communicate from PC to Android phone. There are times when it is a must to use, and times when it is just helpful.
    ADB is used within your recovery or within your OS, but when you are in bootloader mode and need to communicate with your phone then you need fastboot.

    And you may ask why would i ever need this?
    Well many reasons. Main one is knowledge, learning the ins and outs of fastboot, like learning ADB, can get you out of many jams.
    And if you want to unlock your bootloader this is done through fastboot. Granted HTC's unlock is... well crap, but for a Nexus this is how its done.
    One other reason I have to stress is learning for safety reasons, This is about the safest way possible to flash firmware to your phone (ie Radio, Hboot, Recovery)

    Lastly you may want to know the limitations,
    There are many of course, this isnt JTAG, it will not resurrect a hard brick, but it often save peoples phones from 'soft bricks' and lots of time when know how and when to use it.
    Think of fastboot as the program that takes over when ADB cant be used, it works with firmware more than software.

    So where do i get fastboot? There are a few ways but most often I would recommend getting it from the Android SDK as it is will be up to date.
    or you can use THIS HANDY TOOL created by @shimp208

    I will go over the Download and Installation Process in the Next Post
    Then i will go over useful commands.
    *Just a note, This guide is to always be considered under construction as I plan to continue to make additions such as more commands and pictures
    I will continue to attempt to clarifiy when needed and add what I have missed. I have yet to drop any project or guide I have made on XDA and will help where I can
    As always I encourage questions I may miss something or be vague, it is best to understand fully then not ask.
    85
    Setting up fastboot on Windows and Linux

    What is Fastboot?
    Fastboot is a protocol designed to flash signed/unsigned partitions to android phones directly into the phones flash memory. If you are familiar with ADB think of it in the same way.
    If you're not, just understand it is a tool designed to help flash images such as recoveries, bootloaders, kernels, etc. to your android phone. For the most part you can not use much of fastboot unless you are rooted and have an engineering SPL (Hboot/Bootloader)
    If using a Nexus device you in a sense have an engineering bootloader already so don't need to worry about it like HTC folks need. But Some Nexus lines will have different bootloaders with different capabilities.
    This however is not a tutorial to root your phone so i will not explain this. I will though go over SOME basics as in unlocking your bootloader to allow it to be rooted.
    How do I get fastboot for Windows?

    Fastboot.exe can be downloaded to your computer from Google's SDK found
    HERE download the proper package depending on what system you are using.
    also
    you will need the proper drivers to allow your PC and phone to communicate. You will find these in your devices specific forum or possibly you can use PdaNet


    Okay i got it, whats next?
    After you downloaded the SDK package to your PC see where it is located, somewhere like this for Windows
    C:\android\android-sdk-windows\platform-tools
    Of course put it where you like, just know where fastboot.exe lies

    *If you want to skip the SDK, you can get ADB and Fastboot by themselves with THIS HANDY LITTLE TOOL created by shimp208
    Note: After you have ADB and Fastboot you will may want to finish following this guide to add a path in environmental variables.


    For Windows:
    Although not necessary, but to make it easier i really suggest doing these steps:
    left click the Windows (start) button > right click on computer > choose properties > go to advanced system settings > advanced tab > environmental variables > in the first box (user variables for _____) click new > name it
    > the value is the path from earlier
    C:\android\android-sdk-windows\platform-tools
    (yours may differ from this so double check it!) > in the second box (system variables) find a variable named
    if one doesn't exist make one > double click on it > at the very end of the variable value add the same line as before but with a ; in front of it. like this:
    ;C:\android\android-sdk-windows\platform-tools
    alright click ok and you are done!
    EnviromentalVariables.jpg


    Why did I just do all that?
    Well this allows you to open a command line from anywhere on your computer without changing directories to use fastboot. Pretty much we told your PC that when you type
    or
    into CMD where to find it. As you learn how useful fastboot and adb are this will help a lot as CDing to where you want to be is wasted time.

    So I still don't know what to do or how to do it!
    All right lets start simple, click the windows button and in the search field type
    you will notice a window pop up that looks suspiciously like DOS. View attachment 1980110
    Here you will see a blinking cursor after your directory, lets try this type
    Code:
    fastboot
    a whole bunch of probably unfamiliar stuff should now pop up View attachment 1386065 (for the most part this is a list of commands that can be used in fastboot) if you get something like
    fastboot is not recognized as internal or external command operable program or batch file
    then we need to troubleshoot, but for now i will assume it worked.
    Now try typing
    Code:
    fastboot devices
    ...and nothing will happen, Why? because there isn't a device attached. Make sure you have android debugging turned on in your phone (not really needed for fastboot but you do need for ADB), plug it into your computer and boot into fastboot mode. On many phones hold volume down while powering on, if this wont bring you to bootloader mode then see your device specific forum, if needed choose fastboot. Again try typing
    Code:
    fastboot devices
    this time you should have a list of attached devices, this is displayed as the serial number to each. Being many commands will "do" things to your phone try typing
    Code:
    fastboot reboot
    If your phone is now back and running your existing OS, congratulations! :good: You now at least have fastboot set up and working properly. Now lets try a few things out and see why this can be so helpful!


    How do I get fastboot for Linux?

    To get fastboot installed on your Linux box first download appropriate SDK package From Here
    *Not all Linux distros are the same and I don't consider myself a Linux guru, I will explain what I know about the few distributions I've used but remember if something don't work look up specifics for yours HERE
    After SDK is downloaded extract contents into home folder, maybe in a folder called Android, your choice.
    Now we need to make sure we have the latest java JDK installed found HERE or if you prefer you can get it from the terminal
    Code:
    sudo apt-get update
    sudo apt-get install openjdk-6-jdk
    or if using Ubuntu, the software center. (I have heard people complain about JDK7 so to be safe stick with JDK 6 for now)
    **I have a 64bit machine so I needed the 32bit libraries, you may not need this. If you do run this from terminal
    Code:
    sudo apt-get install ia32-libs
    **As pointed out to me by trevd, if you are using Ubuntu 12.10 or newer you should simply open a terminal and run these two commands
    Code:
    sudo apt-get install android-tools-fastboot
    and
    Code:
    sudo apt-get install android-tools-fastboot
    If you never plan on developing for android or using other tools that come with the SDK
    then this should be all you need. And you may also skip the JDK install. As most people will never attempt to create
    an app or ROM or mod their phone in a way that they would need more than this, these simple commands should suffice.


    Downloading Fastboot
    ummm.. isn't that what I just did? Possibly, but as far as I know ADB, fastboot and everything else in platform-tools wont automatically download with the SDK.
    Other have told me it does, so feel free to navigate to the platform-tools folder and see if you see these applications.
    If you skipped installing the SDK and just installed fastboot and ADB from the command line you can skip down to creating a path. So if you got them, skip this, if you don't, do this:
    From in a terminal type
    Code:
    cd ~/android-sdk-linux/tools
    ./android
    **note depending on what you named the folder the downloaded and extracted SDK is in you may need to change your cd command to something else.
    Now a new window will pop up, Click on "Available Packages" and you will be see two boxes. One is Android Repository and the other is Third-party Add-ons.
    Click on "Android Repository" then click on Install Selected. now click on "Accept All" and then click on the Install button.
    Personally I like downloading all that is possible here, you may have limited space or bandwidth so all you 'need' is the contents of platform-tools.
    If you want to download some API's later go for it, they aren't needed unless you are developing.


    Adding a Path
    Just like in windows changing directories can be brutally annoying so lets add a path. Open a Terminal and type:
    Code:
    nano ~/.bashrc
    or you can use gedit, whatever you have/like to use (sudo gedit ~/.bashrc)
    At the end of this text (or at the begining add the following
    Code:
    Android tools
    export PATH=~/android-sdk-linux/platform-tools:~/android-sdk-linux/tools:$PATH
    **again be sure this is your path (neat trick, find fastboot from within platform-tools, right click on it, go to properties, highlight the location/path and copy/paste this)
    Now click save, this will make so you no longer need to type ./adb all the time
    I have been told a reboot is needed here but I don't think so, just type this into a command line:
    Code:
    source ~/.bashrc


    Drivers? I don't need no stinking drivers!
    True, sorta, but more than likely we will need to add the android rules so your device can communicate with PC. Open a Terminal and Type
    Code:
    gksudo gedit /etc/udev/rules.d/51-android.rules
    now add the following lines:
    Code:
    SUBSYSTEM=="usb", ATTRS{idVendor}=="0bb4", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="0502", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="12d1", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="1004", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="22b8", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="04e8", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="0fce", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="0489", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="18d1", SYMLINK+="android_adb", MODE="0666"
    SUBSYSTEM=="usb", ATTRS{idVendor}=="04e8", MODE="0666", GROUP="plugdev"
    Depending on your device this should be all you need and then some, feel free to check out THIS for the most up to date vendor list.
    View attachment 1980099
    Now for a test!
    So plug your phone into PC via usb, have it in fastboot mode (from within bootloader) and open a new terminal, type:
    Code:
    fastboot devices
    If you see a string of #s and letters then success! :good: you are ready to learn the ins and outs of fastboot!
    69
    Using Fastboot To Unlock Your Bootloader

    Do You need to unlock your bootloader?
    For many phones this is necessary to root, for others it is a poor way to root your phone as you may not have full access.
    Many HTC model phones can be rooted with various exploits, sometimes removing the radio secure flags completely.
    If you have one of these devices than I recommend this, as true radio s-off is far superior to an unlocked bootloader.
    But other phones, including the Nexus line, will be fine just unlocking and do not need to worry, Although some phones like the Nexus One can profit from a new bootloader altogether.
    To begin the rooting process you simply need to unlock your bootloader with this command from a terminal/CMD
    Code:
    fastboot oem unlock
    and the reverse of course is
    Code:
    fastboot oem lock

    Be prepared for a full wipe of your phone when unlocking the bootloader!

    But quickly if you have an HTC and choose to unlock your bootloader to root your phone follow these step:
    Select your phone from the list HERE (you will need to create a log in)
    there will be some legal mumbojumbo to click through (just saying you void your warranty but you knew this!)
    you may need HTC sync found HERE as well as the proper RUU for your phone, the HTCDev site will inform you.
    After which the site will move you through the steps to gain fastboot access, but if you followed my guide above just skip it all.
    next you will need to get the identifier token, this is unique to your device and really just getting probably voids your warranty,
    even if you stopped the guide here. to do so, open terminal/CMD and type
    Code:
    fastboot oem get_identifier_token
    copy and paste this information into the prompt at the bottom of the page. Now wait for an email to get your token....
    once you get the email with the token you can now follow their steps to unlock your bootloader...
    really if at all possible i recommend not to do this method of rooting. But if you do, follow these same next steps that the Nexus devices will be doing...


    Now that your bootloader is unlocked:
    We will flash a custom recovery to your phone, then a custom already rooted ROM. To flash the recovery go to your device specific forum HERE and find the developers section.
    Look for a custom recovery option and consider reading up on it there.
    Different Android phones will have different custom recovery options depending on the developers for it. The most common is ClockworkMod, there are both touch and none touch recovery options.
    some others are TWRP, 4EXT, AmonRa and Cannibal. Find out what your options are, pick one and download it.
    If possible check the MD5Sum, Windows use: THIS and Linux use a terminal and type
    Code:
    md5sum <filename>
    of course replace <filename> with the file name.
    View attachment 1980095
    If you prefer, GTK Hash is a nice program as well.
    Now this should be an image not a zip, so if the extension is .img your good, if its in a .zip or .jar or whatever extract the image.
    Take this image and (for simplistic sake) name it
    **if using windows be sure to pay attention if your file extensions are hidden, don't name it recovery.img.img!
    So be sure your phone is in fastboot mode and connected to PC, open a terminal/cmd in the same location that recovery.img is in
    (cd to that directory or windows users can hold shift > right click in the folder it's in > choose open command here)
    Code:
    fastboot erase recovery
    fastboot flash recovery recovery.img
    **erase recovery is not necessary but i am OCD about wiping...
    now if you get an okay! then your good :good:
    Code:
    sending 'recovery' (4930 KB)...
    OKAY [  0.521s]
    writing 'recovery'...
    OKAY [  0.489s]
    finished. total time: 1.10s
    If not let me know what the output is and ill help you fix it. (I will also make a troubleshooting section in my final post)

    Great! Now Let's Flash a ROM
    In that same developers section for your phone, you should pick out a ROM of your licking. If possible i would suggest an older version of CyanogeMod as these builds tend to be quite stable.
    Also some phones may have newer ROMs requiring you to do various things to your phone. Such as changing radios or bootloaders or other things we haven't gotten to yet.
    So for now try to read the OP of the ROM you like and make sure you meet all requirements.
    So Im not going deep into how to flash a ROM from recovery as this is not part of a fastboot guide.
    But pretty much just pick a ROM and anything else you may need (gapps, kernel, etc) and put on root of SDcard (no other folder)
    Then boot to recovery, wipe all you can (I'll teach you fastboot wiping soon!) and then flash ROM + whatever else you need to and then reboot.

    Another Issue With HTC's Unlocked Bootloaders
    Well if this not yet another reason to try to gain true radio s-off for your phone...
    From with in that ROM that you flashed you also need to unzip and extract the kernel (boot.img) this will need to be flashed through fastboot.
    Once all the above steps are completed reboot into fastboot mode, if your recovery doesn't have a quick way to do so just open a terminal/cmd and type:
    Code:
    adb reboot-bootloader
    from here you will need to then open a terminal/cmd in the same location as that boot.img is and type:
    Code:
    fastboot flash boot boot.img
    If it says okay you are finally done!!! Well done with flashing your first ROM but can you flash a ROM in fastboot? I mean do you need recovery at all?
    There are ways, and ill teach ya in the next post!
    55
    Flashing a ROM through Fastboot

    So Why Do I Need To Do This?
    You don't, normally you would flash a ROM through recovery, but why not have another way? Maybe your recovery partition on your phone is corrupt?
    Maybe you just want to say "I learned something new!" whatever your reason here are the simple steps:

    To start:
    We need to download the ROM of choice to your computer. Once complete find the folder that ROM is in and open terminal/cmd to that directory
    (quickest way for windows; just hold shift and right click within that folder > open command window here) of course make sure your phone is plugged into computer and in fastboot mode.

    Lets see how quick and easy this really is...
    In the command line type:
    Code:
    fastboot devices
    Seeing your serial number means we know all is good
    Now lets type these commands:
    Code:
    fastboot erase system -w
    fastboot erase boot
    fastboot update superawesomerom.zip
    Of course replace <superawesomerom.zip> with the correct file name

    and last but not least:
    Code:
    fastboot reboot

    *Its been a little while since i did this but the phone might automatically reboot after flash so no need to run the reboot command

    As your phone boots into the new ROM, pat yourself on the back...

    A Note on Erasing/Formatting
    You may have noticed earlier that I had you erase your recovery before flashing a new one,
    now here I had you erase system and boot, you may be wondering why.
    I find that a large amount of complaints in developer threads are due to people not properly wiping before a flash.
    Of course there is times when a 'dirty' flash is fine, but if you're ever not sure, wipe as cleanly as possible.
    fastboot allows for about the cleanest of wipes by the way. And each partition can be done separately too.
    Code:
    fastboot erase system
    fastboot erase data
    fastboot erase cache
    can all be done individually, but to do these all in one command
    Code:
    fastboot erase system -w
    If possible I recommend to do these steps before flashing a ROM, and now that you know you can do this all within fastboot mode i suggest to try it out, its quick and painless!
    Don't forget to wipe your kernel too! (fastboot erase boot)

    ~Important~ If your device uses an emulated SD card (as in no removable micro SD but an SD partition on phone)
    Then be careful wiping data/userdata as this will erase all contents of internal SD - you are forewarned!

    What about just flashing a single partition?
    Sure this can be done, hell you can restore a nandroid if you want!
    well first you need to make a nandroid back up (unfortunately fastboot cant make a nandroid for you :crying: ) Put it some where on your computer.
    Personally I only keep maybe 2 or 3 nandroids on my phone's SD card as why waste space. I do however keep almost all my nandroids on my computer separated into different folders for different phones. So my path to a nandroid backup would be something like:
    android/htcg2/nandroids/<nameofnandroid>
    But here's the catch, most newer recoveries do tar backups I believe TWRP uses .win, these can not be flashed in their current form!
    However most older recoveries use yaffs2 format for their backups, these will always work. Pretty much if you get a backup with various partitions as .img you're good to go!
    **Hypothetically speaking here: you installed a new recovery and want to flash a nandroid made in old recovery but the two recoveries used different formats...
    Well you can flash the images with fastboot, then make a new nandroid and you got them back!
    ...Maybe I'm stretching... oh well, here's how to!

    Now the obvious stuff:
    Have phone plugged into PC via USB and in fastboot mode, open terminal/cmd and change directories to that folder where your nandroid is in (or again just hold shift and right click > open command window here if using windows)
    Now in terminal/cmd type:

    Code:
    fastboot devices
    all is good when serial number is displayed, now type:
    Code:
    fastboot erase system -w
    fastboot erase boot
    *This isn't 100% necessary but I'm a firm believer in wiping before any flash, even a backup
    Code:
    fastboot flash userdata data.img
    fastboot flash system system.img
    fastboot flash boot boot.img
    fastboot reboot
    (of course change the image names if needed)
    And you did it! :good: now you are almost a pro at using fastboot!
    keep playing around, you'll get the hang of it and will quickly see that this is one of the best tools in the Android SDK.
    It makes things much faster and easier and in many cases safer than the alternatives. Any questions... feel free to ask!
    Happy Flashing!
    44
    What About Flashing Firmware?

    Flashing any firmware to your phone can be dangerous but if possible the best and safest way is with fastboot.
    Hypothetically you flash a new Hboot through recovery and this Hboot was corrupt in some way, if the flash takes you will have a bricked phone, hard bricked, only JTAG can bring it back.
    But with fastboot you get to input your command to terminal/cmd an see the output, if something goes wrong, just DO NOT REBOOT until you fix the problem.
    And again, checking MD5sums is nice when flashing software but a must when flashing firmware.
    I will again recommend THIS for windows and using the terminal for Linux

    Okay, Time To flash A New Bootloader!
    Some phones will not allow bootloader flashes unless you remove the radio secure flags, if you have a phone like this check the developers thread for a how to.
    To begin, find the appropriate bootloader (sometimes referred to as an Hboot or SPL) for your phone,
    Now download and check MD5sum, have your phone in fastboot mode and open a terminal/cmd in the location your Hboot.img is stored.
    Code:
    fastboot devices
    fastboot flash hboot hboot.img
    and of course replace 'hboot.img' with whatever you titled your image
    **Do not reboot if you see 'sending.... failed' need to see the 'okay!'
    I am not trying to scare you as these instances are so rare, but knowing what to do ahead of time is just common sense.

    Not all devices use the same terminology for partitions, so if the above does not work than consider changing to this command:
    Code:
    fastboot flash bootloader bootloader.img
    Again replacing <bootloader.img> with the name of your image

    Now flashing a new bootloader will more than likely repartition your phone, so from here you probably should flash a new recovery, then flash a new ROM.
    Be prepared to do all this before flashing a new Hboot!

    I'm ready to flash a new radio!
    Flashing a radio can also be dangerous, but again the safest way to do so is within fastboot. So if possible always flash radios in fastboot mode!
    **I am not referring to the FM radio in your car, rather your cellular Radio, you know where you get reception... don't ask me how to add a FM radio to your phone!
    Also know OEMs commonly use baseband and radio as interchangeable terms, for the most part this is the exact same thing

    First things first, know why you are flashing a new Radio. Is it because you have poor reception? Poor data speeds? Poor battery life?
    Yes a new radio can cure all this, but NO ONE can tell you which radio is best for your phone, not even someone living in the same city.
    The best radio for my phone will not for sure be the best for yours, even if you live down the road from me. Don't ask what Radio is best! and only flash a radio meant for your device!

    Now that that's out of the way, lets do the same steps as before:
    Download appropriate radio
    Extract if needed (should be in .img format)
    For simplistic sake name it 'radio.img'
    Plug in phone to PC and open a terminal/cmd in the same location as your radio.img
    Code:
    fastboot devices
    fastboot flash radio radio.img
    fastboot reboot-bootloader
    Again only reboot if all goes well (It will if you follow all direction)
    Upon rebooting your bootloader you will notice your radio version has changed, congrats! You're becoming a pro! :D

    *note, occasionally OEMs package another image called rcdata.img along with a firmware release, if they do I also recommend to flash this along with the radio
    Code:
    fastboot flash rcdata rcdata.img
    **another note, if possible try to match the ril libraries between your ROM and radio, this is device specific and you will need to see your developers thread for this info.
    It is not always possible or necessary to do so, but many do say it help quite a lot
    Flashing a Kernel
    Earlier I went over flashing kernels as part of HTC Unlocked Bootloader Flashing, the process is the same for anyone else as well.
    Locate the Kernel you want to flash
    navigate to the folder it is in (should be in .img format and lets name it boot.img)
    Code:
    fastboot flash boot boot.img

    But lets say you are a developer and have worked on a new kernel for your device, a quick and easy way to test it out may be to fastboot load the kernel:
    Code:
    fastboot erase boot
    fastboot boot kernel ramdisk
    As usual replace file/image names accordingly
    If you do not want to erase the current kernel, just skip erasing.
    But I would just have a working kernel.img handy and erase, this way I know there are no residual effects from previous kernel - choice is yours

    Code:
    fastboot flash:raw boot kernel ramdisk 
    fastboot reboot
    Test it out and see how things go! Good luck! :good:

    As always, if you have questions or comments feel free to leave them here!
    Happy Flashing!