[SOLVED] Nexus 5 stuck in boot loop animation (Lollipop) , partially working with 4.4

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eross

Senior Member
May 2, 2015
99
36
I have a Nexus 5 32GB that's about 14 month old. Was running Lollipop 5.1 which was installed through OTA updates (4.44 >5.0 >5.01>5.1). The device is stock and unrooted.
One day, after powering the device up, it went into the boot screen and never managed to finsih the boot (for hours).
After reading extensively on this and other forums , here are the steps I tired , without success:
1. Go to bootloader and press Start
2.Go to bootloader , erase cache
3.Go to bootloader erase user data (factory reset).
I then tried to flash the factory image back. I tried all Lollipop versions from the google developers page of factory images.
starting with 5.1.0 (LMY47I) and going down. All flashing was completed successfully, but the problem remains.
Then I tried 4.4.4 (KTU84P) and the device finally booted up, but it was crippled: Most times It only sees a storage of 16GB , the phone does not recognize any cellular carriers, google play crashes, camera crashes, gallery crashes. An error states that "no external memory is available". Basically it was useless.

I took the phone to an LG lab. They said I need to replace the motherboard. Costs about 200$ !!
I was about to get a new phone , but decided to try one more google search for a fix.
This guide is for any poor soul in the same state.
This issue can be solved without replacing the motherboard for 200$.

The problem in my case was that the /persist partition was degraded, and could not mount.
I found out by trying to follow this guide: http://android.stackexchange.com/qu...dots-lollipop-screen-after-hard-factory-reset
I got as far as activating ADB Sideload when I got the error "cannot mount /persist".
This is a software problem.
Her's how to fix it (It's a long and detailed guide - but worth the result):

First, you must enable USB debugging mode , if it was not enabled (if it is enabled you can skip the first step of this guide) . The way to do that is to flash a stock image that will load, even if not fully working. In my case I could flash version 4.4x and get the phone to load. I am not aware of any other way to enable USB debugging, other than from within a working OS. If someone knows a way - please post it.

The easiest way I found to flash my phone is using Julian OS' script. You can download the stock image5.0 and 5.01 with the script from here:
https://www.androidfilehost.com/?w=files&flid=22367
You will need to adapt the 4.4x firmware to have the script flash it, but it's very easy, just a couple of files to rename.
When you open Julian's zip file you will see that he uses a script that flashes the firmware's images one by one. What I did was download the stock images from Google https://developers.google.com/android/nexus/images , used winrar to extracrt all the files from the .tgz file to a folder, then unzip the only zip file there (image-hammerhead-xxxxx.zip) which contains 5 img files. I then renamed the radio-hammerhead-xxxxx.img to radio.img and bootloader-hammerhead-xxxx.img to bootloader.img. Now all the file names comply with Julian's script. From Julian's archive copy the files "From Bootloader.bat" and "fastboot.exe" to the folder where all the images you just renamed are.
Put the phone in bootloader mode (turn the phone off, press the Vol- and the power buttons). Once the the phone is in bootloader mode, connect it to the PC and run "From Bootloader.bat" and follow the onscreen instructions. In about 2 minutes, your phone will be flashed.

Turn the phone on, it should load the OS. Disregard all the error messages, and don't bother setting the phone up. If you skip wifi, and don't have a sim in the phone you can finish the basic setup quickly.
Next you need to get developer tools activated: Settings>about phone>Build number. Tap 7 times on the build number and this will unlock Developer tools. Go back to settings and the new Developer Tools and enable usb debugging. Approve any popups.

*** I am not aware of how to enable usb debugging if you cannot go into the settings. If non of the stock images loads for you, search for a way to get usb debugging working , or else you cannot continue. You need this for ADB to connect to the phone.****

Next, you need to have ADB on your PC, and it should be able to reach your phone. If you already have - then skip to the next step. If you don't - then here is how to get the latest version:
Go here and download the installer https://developer.android.com/sdk/index.html#Other
Install the file and when it's done run SDK manager. Choose only the first 2 tools (Android sdk tools and Platform tools), this will install the latest adb and fastboot tools. To make sure all is installed open a command prompt (Click Start, type cmd in the search and run cmd.exe) and type adb. You should see all the adb possible commands typed. Now you can test if your phone can be reached by adb: connect your phone (remember usb debugging must be on!) and type: adb devices. After a few seconds you should see something like this:
List of devices attached
024703f599cc8feb device

If you get this, it means you have usb debugging enabled and a proper usb driver installed and you can go to the next step . If there is no device in the list you need to install/update the USB driver:

You have to make sure that when you connect your phone with USB debugging on, you have 2 entries in Winodws Device manager:
Under Portable devices >Nexus 5 , and under Android device> Android composite ADB Interface.
If the second one is missing, ADB will not work and you can't continue. There are 2 ways to fix that :

1. You can install an Android driver called Universal Naked Driver 0.73 from here: http://xdaforums.com/showthread.php?t=2386956. Unzip the file to a folder.
The author of that guide states you need to uninstall any driver that already exists. This proved tricky because Windows would not uninstall the Nexus 5 driver. I decided to install it on a PC that has no android driver.
When you connect the phone to a windows 7 pc for the first time it will search for a driver. I disconnected the internet and windows installed a generic driver. In device manager I saw Nexus 5 with a yellow triangle. I Right clicked on it > update driver software > Browse my computer for driver software and point to the folder you unzipped the driver. You will get a warning - allow the installation.

2. If that does not work or if you don't have another "virgin" PC try this:
Run SDK Manager, under Extras mark Google USB driver. You don't need anything else marked. Install the driver.
Now connect your phone to the PC in normal mode (not bootloader!) . Open device manager. You should have two entries: Portable devices >Nexus 5 and Android device > Android Composite ADB Interface
If the second one is missing, but the Nexus 5 is properly installed, Right click on the Nexus 5 device >Update driver software > Browse my computer for driver software >Let me pick from a list. Now make sure that "Show compatible Hardware" is ticked . You should now have an entry called "USB composite device". Choose that and let it install. When it's done, if you still have an an Unknown device >Nexus 5 and no Android Composite ADB Interface in device manager, then unplug the phone and reconnect it again . You should now have both devices installed.
If by chance this does not work, and you have a Nexus 5 with a yellow error , right click it>update software driver> Browse my computer.> and point it to the Universal Naked Driver folder or the SDK>Extras>Google USB driver folder and it should update so both devices appear (Nexus 5 and ADB).


Once adb can see your pohne go here, to read bitdomo's guide to fix the broken persist partition.
http://xdaforums.com/google-nexus-5/general/guide-to-fix-persist-partition-t2821576

There are some prerequisites to getting this to work:

The first one is that the phone can be reached by ADB, this is why you needed the usb debugging mode to be turned on, and the proper usb driver installed.

Second, you need to install a custom recovery image. Don't worry, you will overwrite it later. The one I used is TWRP. Get the latest version from here:
http://techerrata.com/browse/twrp2/hammerhead
To install I recommend you copy Fastboot.exe and the TWRP file to an empty folder on your PC . Rename the TWRP file to "recovery.img". Open a command prompt in the folder (see here if you don't know how http://www.techsupportalert.com/content/how-open-windows-command-prompt-any-folder.htm) , in the black window type: fastboot flash recovery recovery.img and hit Enter. Wait a few seconds and it will finish.

Last, you need to root your device. There are many ways to do this. I did this very simply by downloading CF-Auto-Root from https://autoroot.chainfire.eu/ The file you need is this: https://download.chainfire.eu/363/CF-Root/CF-Auto-Root/CF-Auto-Root-hammerhead-hammerhead-nexus5.zip . Unzip it, put your phone in bootloader, run root-windows.bat.
Now you are prepaired... Follow the guide by bitdomo . Open a command prompt , and run the 2 commands bitdomo wrote. You will get a series of questions , type y followed by Enter until it's all done.
SInce you are still in bootloader mode, and a big START is at the top of the screen, click the power button to reboot. Now your oS 4.4x should load properly. Make sure everything is working.
I did not follow the steps for the wifi and BT fix , because they worked fine (and still do 4 months later) , but you can go ahead and do that too.

Now you can flash to the latest firmware 5.10 - download the file from the developer site I gave before, use Jason Os's script to flash the image, and lock the device. Done! Boot up the device and make sure it recognizes the right amount of RAM on your phone (16 or 32GB). If it does, then all is well .
When I first booted the device , I saw that it only recognized 16GB instead of 32GB. To solve this install TWRP again, go to Wipe>Format data . Then reboot the device and make sure you have 32GB.
If you like the stock recovery instead of TWRP you can use Fastboot to flash the original recovery.img.
Now you have a working Nexus 5 , v5.10.


Thanks to LyricWulf and bitdomo for their life saving guides. I hope this helps others in the same spot, and saves them 200$ .
 
Last edited:

killian.1140

New member
May 6, 2015
2
0
stuck at unlock step

how u unlock nexus 5 when stuck booplop n cnt go to android screen?alrdy using ths step "fastboot oem unlock" when i reboot for unlock,stuck at bootloop n alrdy w8ing 24hr still bootloop cnt see android home screen...n i go to restart nexus5,n locked again... i just stuck on this place,cnt go to next step..pls help me
sry my englsh so bad
 

pashkustva

Senior Member
Mar 18, 2011
54
4
Kaunas
Thanks! Helped me to save my N5!
Do not need to exactly as it is posted but the directions is good!

Thanks again.
 

eross

Senior Member
May 2, 2015
99
36
how u unlock nexus 5 when stuck booplop n cnt go to android screen?alrdy using ths step "fastboot oem unlock" when i reboot for unlock,stuck at bootloop n alrdy w8ing 24hr still bootloop cnt see android home screen...n i go to restart nexus5,n locked again... i just stuck on this place,cnt go to next step..pls help me
sry my englsh so bad
Not sure what your problem is, but if you are stuck at the boot screen (with the colored dots spinning) you might have the smae problem I describe. You can try to go to bootloader and wipe the cache, if that does not help and you don't mind a wiping all your data do a factory reset. , Go to recovery mode (third option in bootloader), then press the powr and vol up buttons together several times until you get into recovery. Then choose what you want to wipe.
If that does not restore your phone you need to follow my guide. Probably your persist partion is degraded and needs to be fixed. If you follow my guide you will find out what your problem is.
Good luck
 
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volvoxxda

Member
Apr 8, 2013
13
1
Podgorica
I had the same problem, and for me, simple NAND restore from TWRP recovery solved this issue. I recently made this NAND backup for no reason and it happens to be a very good move. Cheers
 
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eross

Senior Member
May 2, 2015
99
36
I had the same problem, and for me, simple NAND restore from TWRP recovery solved this issue. I recently made this NAND backup for no reason and it happens to be a very good move. Cheers

But for that you have had to install TWRP in the first place...
Mine was stock.
Where is the backup saved?
 

volvoxxda

Member
Apr 8, 2013
13
1
Podgorica
Mine was rooted + TWRP recovery and I saved my backup on flash drive with TWRP's backup option. I was able to boot into boot menu (pwr + vol-) and it would let me to enter into TWRP only. For me it was enough to initiate a restore process..
 

eross

Senior Member
May 2, 2015
99
36
Mine was rooted + TWRP recovery and I saved my backup on flash drive with TWRP's backup option. I was able to boot into boot menu (pwr + vol-) and it would let me to enter into TWRP only. For me it was enough to initiate a restore process..

Flash drive? Do you mean the Nexus internal memory?
 

volvoxxda

Member
Apr 8, 2013
13
1
Podgorica
7b5f726ffaa82681c56d99fa4eef866e.jpg


External, like on this picture.
 
Last edited:

volvoxxda

Member
Apr 8, 2013
13
1
Podgorica
Final solution: power button micro tactile switch was faulty, causing boot loop from time to time. Replacing that little bastard solved this heartbreaking issue :)
 

WarriorMax

Senior Member
Jun 10, 2011
507
175
worked

worked great. confusing in the start but got it working. Thanks for a life saving guide for nexus 5
 

Lukasliud

New member
Jul 8, 2015
1
0
incredible :)

Hi eross,
I registered and logged in just to say thank you for this amazing tutorial. I've been trying to repair my N5 for about 12 hours, and I was about to give up when I saw this post. You saved my Nexus!!
Thanks again. :victory::highfive::good:
 

ambervals6

Senior Member
Jun 14, 2015
828
213
Not sure what your problem is, but if you are stuck at the boot screen (with the colored dots spinning) you might have the smae problem I describe. You can try to go to bootloader and wipe the cache, if that does not help and you don't mind a wiping all your data do a factory reset. , Go to recovery mode (third option in bootloader), then press the powr and vol up buttons together several times until you get into recovery. Then choose what you want to wipe.
If that does not restore your phone you need to follow my guide. Probably your persist partion is degraded and needs to be fixed. If you follow my guide you will find out what your problem is.
Good luck

What if you cannot even get into recovery because it is missing?

Sent from my SM-G920T
 
Jul 11, 2015
9
0
help

This is a Nexus 5 32GB that's about 14 month old. Was running Lollipop 5.1 which was installed through OTA updates (4.44 >5.0 >5.01>5.1). The device is stock and unrooted.
Yesterday after powering the device up, it went into the boot screen and never managed to finsih the boot (for hours).
After reading extensively on this and other forums , here are the steps I tired , without success:
1. Go to bootloader and press Start
2.Go to bootloader , erase cache
3.Go to bootloader erase user data (factory reset).
I then tried to flash the factory image back. I tried all Lollipop versions from the google developers page of factory images. (can't post links yet...)
starting with 5.1.0 (LMY47I) and going down. All flashing was completed successfully, but the problem remains.
Then I tried 4.4.4 (KTU84P) and the device finally booted up, but it is crippled: Most times It only sees a storage of 16GB , the phone does not recognize any cellular carriers, google play crashes, camera crashes, gallery crashes. An error states that "no external memory is available". Basically it is useless.

I am wondering if it is a software or hardware problem. It appears as though part of the phone's memory is not functioning . Is there a way to check this? Is there a way to fix this?
Thanks

Edit: Just came back from an LG lab. Bad news. Need to replace the motherboard. Costs about 200$ !! Can't find anything cheaper on ebay. Guess it's time for a new phone :(

Edit #2 - SOLVED !!:laugh:
OK, this for any poor soul in the same state. This issue can be solved without replacing the motherboard for 200$.
The problem in my case was that the /persist partition was degraded, and could not mount. Here is how I found it out, and how I fixed it:

First, try to flash a stock image that will load, even if not fully working. You will need this later. In my case I could flash version 4.4x and get the phone to load.

The easiest way I found to flash my phone is using Julian OS' script. You can download the stock image5.0 and 5.01 with the script from here:
https://www.androidfilehost.com/?w=files&flid=22367
You will need to adapt the 4.4x firmware to have the script flash it, but it's very easy, just a couple of files to rename.
When you open Julian's zip file you will see that he uses a script that flashes the firmware's images one by one. What I did was download the stock images from Google https://developers.google.com/android/nexus/images , used winrar to extracrt all the files from the .tgz file to a folder, then unzip the only zip file there (image-hammerhead-xxxxx.zip) which contains 5 img files. I then renamed the radio-hammerhead-xxxxx.img to radio.img and bootloader-hammerhead-xxxx.img to bootloader.img. Now all the file names comply with Julian's script. From Julian's archive copy the files "From Bootloader.bat" and "fastboot.exe" to the folder where all the images you just renamed are.
Put the phone in bootloader mode (turn the phone off, press the Vol- and the power buttons). Once the the phone is in bootloader mode, connect it to the PC and run "From Bootloader.bat" and follow the onscreen instructions. In about 2 minutes, your phone will be flashed.
Turn the phone on, if you are lucky it will load the OS. Disregard all the error messages, and don't bother setting the phone up. If you skip wifi, and don't have a sim in the phone you can finish the basic setup quickly.
Next you need to get developer tools activated: Settings>about phone>Build number. Tap 7 times on the build number and this will unlock Developer tools. Go back to settings and the new developer tools and enable usb debugging. Approve any popups.
I am not aware of how to enable usb debugging if you cannot go into the settings. If non of the stock images loads for you, search for a way to get usb debugging working , or else you cannot continue. You need this for ADB to connect to the phone.
Once this is done , boot the phone into debugging mode.
Read the guide here http://android.stackexchange.com/qu...dots-lollipop-screen-after-hard-factory-reset
I got as far as activating ADB Sideload when I got the error "cannot mount /persist". I then understood what the problem was. If you get the same error - you are in luck!
Then go here, to learn how to fix the broken persist partition.
http://xdaforums.com/google-nexus-5/general/guide-to-fix-persist-partition-t2821576
There are some prerequisites to getting this to work.
The first one is that the phone can be reached by ADB, this is why you needed the usb debugging mode.
Second, you need to install a custom recover image. Don't worry, you will overwrite it later. The one I used is TWRP. Get the latest version from here:
http://techerrata.com/browse/twrp2/hammerhead
To install I recommend you copy Fastboot.exe and the TWRP file to an empty folder on your PC . Rename the TWRP file to "recovery.img". Open a command prompt in the folder (see here if you don't know how http://www.techsupportalert.com/content/how-open-windows-command-prompt-any-folder.htm) , in the black window type: fastboot flash recovery recovery.img and hit Enter. Wait a few seconds and it will finish.
Third, you need to install an Android driver called Universal Naked Driver 0.73 from here: http://xdaforums.com/showthread.php?t=2386956. Unzip the file to a folder.
Since the author of that guide states you need to uninstall any driver that already exists, I decided to install it on a PC that has no android driver. When you connect the phone to a windows 7 pc for the first time it will search for a driver. I disconnected the internet and windows installed a generic driver. In device manager I saw Nexus 5 with a yellow triangle. I Right clicked on it > update driver software > Browse my computer for driver software and point to the folder you unzipped the driver. You will get a warning - allow the installation.
Last, you need to root your device. (I think this can also be done from within TWRP , but I am not sure how...) I did this very simply by downloading CF-Auto-Root from https://autoroot.chainfire.eu/ The file you need is this: https://download.chainfire.eu/363/CF-Root/CF-Auto-Root/CF-Auto-Root-hammerhead-hammerhead-nexus5.zip . Unzip it, put your phone in bootloader, run root-windows.bat.
Now you are prepaired... Follow the guide by bitdomo . Open a command prompt where adb.exe is located , and run the 2 commands bitdomo wrote. You will get a series of questions , type y followed by Enter until it's all done.
SInce you are still in bootloader mode, and a big START is at the top of the screen, click the power button to reboot. Now your oS 4.4x should load properly. Make sure everything is working.
Now you can flash to the latest firmware 5.10 - download the file from the developer site I gave before, use Jason Os's script to flash the image, and lock the device.
When I first booted the device , I saw that it only recognized 16GB instead of 32GB. To solve this install TWRP again, go to Wipe>Format data . Then reboot the device and make sure you have 32GB.
If you like the stock recovery instead of TWRP you can use Fastboot to flash the original recovery.img.
Now you have a working Nexus 5 , v5.10.
Thanks to LyricWulf and bitdomo for their life saving guides. I hope this helps others in the same spot, and saves them 200$ .

Addendum: According to bitdomo, installing a custom recovery like TWRP enables USB debugging by default even if the phone does not boot. I have not tried this myself, but this means you can foergo installing os 4.4x , and go straight to ADB and run the command that fixes the persist partition.
Go ahead and try it. It will save you a lot of time!

My N5 has exact problem as yours even same errors of camera and playstorw crashing when i loaded older android version.. now im positive your instructions will help me but im having some trouble with your steps i do not know how to type comnands with ADB .. im truly novice and dont want to damage the phone more could you simplify the steps or make a video please? Thank you
 

eross

Senior Member
May 2, 2015
99
36
Sorry, I can't make it any simpler than that. I can't make a video now because my phone is fixed. Adb is very simple, it's like an old DOS window where you type the text. I would follow Bitdomo's advice and start by installing TWRP. This will get you USB debugging, and you can run ADB and follow his instructions to fix the persist partition.
 

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    I have a Nexus 5 32GB that's about 14 month old. Was running Lollipop 5.1 which was installed through OTA updates (4.44 >5.0 >5.01>5.1). The device is stock and unrooted.
    One day, after powering the device up, it went into the boot screen and never managed to finsih the boot (for hours).
    After reading extensively on this and other forums , here are the steps I tired , without success:
    1. Go to bootloader and press Start
    2.Go to bootloader , erase cache
    3.Go to bootloader erase user data (factory reset).
    I then tried to flash the factory image back. I tried all Lollipop versions from the google developers page of factory images.
    starting with 5.1.0 (LMY47I) and going down. All flashing was completed successfully, but the problem remains.
    Then I tried 4.4.4 (KTU84P) and the device finally booted up, but it was crippled: Most times It only sees a storage of 16GB , the phone does not recognize any cellular carriers, google play crashes, camera crashes, gallery crashes. An error states that "no external memory is available". Basically it was useless.

    I took the phone to an LG lab. They said I need to replace the motherboard. Costs about 200$ !!
    I was about to get a new phone , but decided to try one more google search for a fix.
    This guide is for any poor soul in the same state.
    This issue can be solved without replacing the motherboard for 200$.

    The problem in my case was that the /persist partition was degraded, and could not mount.
    I found out by trying to follow this guide: http://android.stackexchange.com/qu...dots-lollipop-screen-after-hard-factory-reset
    I got as far as activating ADB Sideload when I got the error "cannot mount /persist".
    This is a software problem.
    Her's how to fix it (It's a long and detailed guide - but worth the result):

    First, you must enable USB debugging mode , if it was not enabled (if it is enabled you can skip the first step of this guide) . The way to do that is to flash a stock image that will load, even if not fully working. In my case I could flash version 4.4x and get the phone to load. I am not aware of any other way to enable USB debugging, other than from within a working OS. If someone knows a way - please post it.

    The easiest way I found to flash my phone is using Julian OS' script. You can download the stock image5.0 and 5.01 with the script from here:
    https://www.androidfilehost.com/?w=files&flid=22367
    You will need to adapt the 4.4x firmware to have the script flash it, but it's very easy, just a couple of files to rename.
    When you open Julian's zip file you will see that he uses a script that flashes the firmware's images one by one. What I did was download the stock images from Google https://developers.google.com/android/nexus/images , used winrar to extracrt all the files from the .tgz file to a folder, then unzip the only zip file there (image-hammerhead-xxxxx.zip) which contains 5 img files. I then renamed the radio-hammerhead-xxxxx.img to radio.img and bootloader-hammerhead-xxxx.img to bootloader.img. Now all the file names comply with Julian's script. From Julian's archive copy the files "From Bootloader.bat" and "fastboot.exe" to the folder where all the images you just renamed are.
    Put the phone in bootloader mode (turn the phone off, press the Vol- and the power buttons). Once the the phone is in bootloader mode, connect it to the PC and run "From Bootloader.bat" and follow the onscreen instructions. In about 2 minutes, your phone will be flashed.

    Turn the phone on, it should load the OS. Disregard all the error messages, and don't bother setting the phone up. If you skip wifi, and don't have a sim in the phone you can finish the basic setup quickly.
    Next you need to get developer tools activated: Settings>about phone>Build number. Tap 7 times on the build number and this will unlock Developer tools. Go back to settings and the new Developer Tools and enable usb debugging. Approve any popups.

    *** I am not aware of how to enable usb debugging if you cannot go into the settings. If non of the stock images loads for you, search for a way to get usb debugging working , or else you cannot continue. You need this for ADB to connect to the phone.****

    Next, you need to have ADB on your PC, and it should be able to reach your phone. If you already have - then skip to the next step. If you don't - then here is how to get the latest version:
    Go here and download the installer https://developer.android.com/sdk/index.html#Other
    Install the file and when it's done run SDK manager. Choose only the first 2 tools (Android sdk tools and Platform tools), this will install the latest adb and fastboot tools. To make sure all is installed open a command prompt (Click Start, type cmd in the search and run cmd.exe) and type adb. You should see all the adb possible commands typed. Now you can test if your phone can be reached by adb: connect your phone (remember usb debugging must be on!) and type: adb devices. After a few seconds you should see something like this:
    List of devices attached
    024703f599cc8feb device

    If you get this, it means you have usb debugging enabled and a proper usb driver installed and you can go to the next step . If there is no device in the list you need to install/update the USB driver:

    You have to make sure that when you connect your phone with USB debugging on, you have 2 entries in Winodws Device manager:
    Under Portable devices >Nexus 5 , and under Android device> Android composite ADB Interface.
    If the second one is missing, ADB will not work and you can't continue. There are 2 ways to fix that :

    1. You can install an Android driver called Universal Naked Driver 0.73 from here: http://xdaforums.com/showthread.php?t=2386956. Unzip the file to a folder.
    The author of that guide states you need to uninstall any driver that already exists. This proved tricky because Windows would not uninstall the Nexus 5 driver. I decided to install it on a PC that has no android driver.
    When you connect the phone to a windows 7 pc for the first time it will search for a driver. I disconnected the internet and windows installed a generic driver. In device manager I saw Nexus 5 with a yellow triangle. I Right clicked on it > update driver software > Browse my computer for driver software and point to the folder you unzipped the driver. You will get a warning - allow the installation.

    2. If that does not work or if you don't have another "virgin" PC try this:
    Run SDK Manager, under Extras mark Google USB driver. You don't need anything else marked. Install the driver.
    Now connect your phone to the PC in normal mode (not bootloader!) . Open device manager. You should have two entries: Portable devices >Nexus 5 and Android device > Android Composite ADB Interface
    If the second one is missing, but the Nexus 5 is properly installed, Right click on the Nexus 5 device >Update driver software > Browse my computer for driver software >Let me pick from a list. Now make sure that "Show compatible Hardware" is ticked . You should now have an entry called "USB composite device". Choose that and let it install. When it's done, if you still have an an Unknown device >Nexus 5 and no Android Composite ADB Interface in device manager, then unplug the phone and reconnect it again . You should now have both devices installed.
    If by chance this does not work, and you have a Nexus 5 with a yellow error , right click it>update software driver> Browse my computer.> and point it to the Universal Naked Driver folder or the SDK>Extras>Google USB driver folder and it should update so both devices appear (Nexus 5 and ADB).


    Once adb can see your pohne go here, to read bitdomo's guide to fix the broken persist partition.
    http://xdaforums.com/google-nexus-5/general/guide-to-fix-persist-partition-t2821576

    There are some prerequisites to getting this to work:

    The first one is that the phone can be reached by ADB, this is why you needed the usb debugging mode to be turned on, and the proper usb driver installed.

    Second, you need to install a custom recovery image. Don't worry, you will overwrite it later. The one I used is TWRP. Get the latest version from here:
    http://techerrata.com/browse/twrp2/hammerhead
    To install I recommend you copy Fastboot.exe and the TWRP file to an empty folder on your PC . Rename the TWRP file to "recovery.img". Open a command prompt in the folder (see here if you don't know how http://www.techsupportalert.com/content/how-open-windows-command-prompt-any-folder.htm) , in the black window type: fastboot flash recovery recovery.img and hit Enter. Wait a few seconds and it will finish.

    Last, you need to root your device. There are many ways to do this. I did this very simply by downloading CF-Auto-Root from https://autoroot.chainfire.eu/ The file you need is this: https://download.chainfire.eu/363/CF-Root/CF-Auto-Root/CF-Auto-Root-hammerhead-hammerhead-nexus5.zip . Unzip it, put your phone in bootloader, run root-windows.bat.
    Now you are prepaired... Follow the guide by bitdomo . Open a command prompt , and run the 2 commands bitdomo wrote. You will get a series of questions , type y followed by Enter until it's all done.
    SInce you are still in bootloader mode, and a big START is at the top of the screen, click the power button to reboot. Now your oS 4.4x should load properly. Make sure everything is working.
    I did not follow the steps for the wifi and BT fix , because they worked fine (and still do 4 months later) , but you can go ahead and do that too.

    Now you can flash to the latest firmware 5.10 - download the file from the developer site I gave before, use Jason Os's script to flash the image, and lock the device. Done! Boot up the device and make sure it recognizes the right amount of RAM on your phone (16 or 32GB). If it does, then all is well .
    When I first booted the device , I saw that it only recognized 16GB instead of 32GB. To solve this install TWRP again, go to Wipe>Format data . Then reboot the device and make sure you have 32GB.
    If you like the stock recovery instead of TWRP you can use Fastboot to flash the original recovery.img.
    Now you have a working Nexus 5 , v5.10.


    Thanks to LyricWulf and bitdomo for their life saving guides. I hope this helps others in the same spot, and saves them 200$ .
    2
    I get the second one (smaller dots).

    For some reason you are still stuck on Android 5 . That is why you cannot boot in. You need to flash 4.4 to be able to boot in and enable USB debugging.
    1
    how u unlock nexus 5 when stuck booplop n cnt go to android screen?alrdy using ths step "fastboot oem unlock" when i reboot for unlock,stuck at bootloop n alrdy w8ing 24hr still bootloop cnt see android home screen...n i go to restart nexus5,n locked again... i just stuck on this place,cnt go to next step..pls help me
    sry my englsh so bad
    Not sure what your problem is, but if you are stuck at the boot screen (with the colored dots spinning) you might have the smae problem I describe. You can try to go to bootloader and wipe the cache, if that does not help and you don't mind a wiping all your data do a factory reset. , Go to recovery mode (third option in bootloader), then press the powr and vol up buttons together several times until you get into recovery. Then choose what you want to wipe.
    If that does not restore your phone you need to follow my guide. Probably your persist partion is degraded and needs to be fixed. If you follow my guide you will find out what your problem is.
    Good luck
    1
    I had the same problem, and for me, simple NAND restore from TWRP recovery solved this issue. I recently made this NAND backup for no reason and it happens to be a very good move. Cheers
    1
    Does the bootloader remain unlocked when the phone is rebooted? I ask because a write failure is often due to a locked bootloader.

    Did you flash the userdata.img file?