Flatline - Unbrickable Nexus 7 (Wi-Fi + 3G)

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rayman

Senior Recognized Developer
May 1, 2008
278
1,399
The AndroidRoot.Mobi Team is proud to present Flatline: Nvflash for Nexus 7 & Nexus 7 3G (2012)

This release allows generating nvflash blobs for your specific device, making your device unbrickable as long as you have a copy of the blobs.
As a brand new feature, it will also enable wifi and upload a copy of the blob to androidroot's server. Later, a solution will be released to retrieve the blobs from the server if you ever loose them.

https://www.androidroot.mobi/pages/guides/tegra3-guide-nvflash-jellybean/

Credit goes to the AndroidRoot.Mobi team:
Bumble-Bee (Apache14), IEF, kmdm, lilstevie & RaYmAn.
 

rayman

Senior Recognized Developer
May 1, 2008
278
1,399
Ah yes! This makes updating the bootloader a less scary procedure. (It happened to me and I had to send an RMA request. Fortunately, they accepted it.) I do have a question. Are the blobs hardware specific for the Nexus 7? (Flashing someone's Nexus 7 dump to mine.)

Sent from my Nexus 7 using xda app-developers app

The blobs are device-specific. They will only works on your particular device and no one elses.
Otherwise, we would have just released pre-made blobs :)
 

dragonnn

Senior Member
Oct 16, 2011
1,136
861
Hi! I have tried to nvflash my TF300T with the new guide, but after generating the blob.bin and run whille I am getting an error:
Code:
Wheelie 0.1 - Preflight for nvflash.
Copyright (c) 2011-2012 androidroot.mobi
========================================

Waiting for device in APX mode...
[=] Chip UID: 0x15d2d4228340213
[-] Incorrect BLOB selected. nverror: 0x4.

Seems like the bootloader didn't flash the first time - after the second try and regenerating the nvflash files it works.
 
Last edited:

t1.8matt

Senior Member
Jan 22, 2012
1,923
419
Pittsburgh, PA.
so the guide on androidroots website should be followed before you start tinkering with your device? just wondering. I have an N7, but have never messed it up to the point where fastbooting the factory image doesn't work. only killed it due to a hardware error :)
 

TeCKNeiC

Senior Member
Jan 25, 2010
116
78
Can you still use this if you can only access the APX mode due to a bricked tablet?
 

lilstevie

Senior Recognized Developer
Apr 17, 2009
1,339
1,040
[/COLOR]I successfully backed up the blobs and partition images. I'm happy someone finally found a unbrickable solution. However, I tried flashing back the stock bootloader (4.23) but it displayed "Signature mismatch." in red on the top left corner and failed. (Luckily, I can still interactive with the bootloader menu.) Would flashing a ZIP with the image inside work as a workaround? Is there a special procedure that I have to perform? Are you going to release a modified 4.23 bootloader?

Try flashing the bootloader with nvflash rather than fastboot, flashing the bootloader from fastboot and recovery is subject to a signature check.
 

lilstevie

Senior Recognized Developer
Apr 17, 2009
1,339
1,040
Wouldn't that flash the modified bootloader? Also, I can't find instructions on flashing the bootloader under NVFlash.

if you have any bootloader you can flash it with nvflash easily. nvflash -r --download 4 bootloader.bin and it will flash, this isn't just limited to the stock bootloaders either, you can use this to attempt porting other bootloaders like u-boot.
 

lilstevie

Senior Recognized Developer
Apr 17, 2009
1,339
1,040
I ran out of thanks... Thanks...

Edit: So I rename "bootloader-grouper-4.23.img" from the factory image archive to "bootloader.bin" or is it something else entirely? Just double checking before I screw any partitions...again.

doesn't matter what it is called I just used bootloader.bin as an example

Code:
nvflash -r --download 4 $filename

is probably the most appropriate way to represent it where $filename is whatever you called the bootloader
 

heavy_metal_man

Senior Member
Nov 6, 2011
2,749
752
Does this mean with this we would be able to make a bootloader with custom splash screens?? :confused:

Sent from my Nexus 7 using Tapatalk 4
 

heavy_metal_man

Senior Member
Nov 6, 2011
2,749
752
if you wanted you could try yes. not too sure about the format the current splash is though

Hmmm. This is great work :D do you know if anyone on any of the other Asus devices have succeeded in changing the splash screen? That may be a good place to start looking. I shall look into this :)

Sent from my Nexus 7 using Tapatalk 4
 

lilstevie

Senior Recognized Developer
Apr 17, 2009
1,339
1,040
Hmmm. This is great work :D do you know if anyone on any of the other Asus devices have succeeded in changing the splash screen? That may be a good place to start looking. I shall look into this :)

Sent from my Nexus 7 using Tapatalk 4

Nope, but afaik it is a standard format across tegra devices, so maybe look up other tegra based devices as a starting point
 

lilstevie

Senior Recognized Developer
Apr 17, 2009
1,339
1,040
This is probably going to annoy you a lot. I tried holding the power button for more than 30 seconds and doing weird button combinations but it still wouldn't get recognized. Should I try draining the battery? (I have a feeling it might take quite some time...)

I'm one of the only androidroot members who doesn't own an N7 so I will have to defer to one of the others for where to go, but I do believe one of them has ended up in a similar situation but managed to get out of it.

OK cool, any ideas on where I can get a start on decompiling the bootloader to have a look at its internals?

Sent from my Nexus 7 using Tapatalk 4

IDA would be the best place to start
 
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lkspooky

Member
Nov 3, 2012
45
13
San Diego, CA
I know how to install the 4.23 bootloader...

Step 1: Get into fastboot by... Well if you don't know how to get into fastboot then why did you do this???
Step 2: Get the unmodified 4.13 bootloader (attached as 413bl.img ) and flash it by using" fastboot flash bootloader 413bl.IMG"
Step 3: Reboot into bootloader using volume keys
Step 4: Flash the 4.23 bootloader (attached as bootloader-grouper-4.23.img )
Step 5: Reboot
Step 6: ???
Step 7: Profit
 

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  • 413bl.img
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  • bootloader-grouper-4.23.img
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Last edited:

lkspooky

Member
Nov 3, 2012
45
13
San Diego, CA
Remove the battery and try again...

Alright, thanks. I'll keep updated on this topic for the solution.

I became way too courageous... I actually need my tablet for school so please find it soon. (No pressure. :p)
Pop off the back cover using a guitar pick or fingernails and remove the battery cable and try to get into NVflash. If you don't know how to unplug the battery go onto ifixit and search for N7 disassembly
 

lilstevie

Senior Recognized Developer
Apr 17, 2009
1,339
1,040
Alright, thanks. I'll keep updated on this topic for the solution.

I became way too courageous... I actually need my tablet for school so please find it soon. (No pressure. :p)

Code:
18:10 <@RaYmAn> you have to hold down uhm, all buttons or something for like 10 seconds, while it's plugged in
18:10 <@RaYmAn> and then you have to let go of power and voldown at *just* the right time

but make sure you charge the battery for a bit first with the charger in case the battery is starting to run low
 

wildestpixel

Senior Member
Aug 25, 2011
1,016
548
London
Step 1: Get into fastboot by... Well if you don't know how to get into fastboot then why did you do this???
Step 2: Get the unmodified 4.13 bootloader (attached as 413bl.img ) and flash it by using" fastboot flash bootloader 413bl.IMG"
Step 3: Reboot into bootloader using volume keys
Step 4: Flash the 4.23 bootloader (attached as bootloader-grouper-4.23.img )
Step 5: Reboot
Step 6: ???
Step 7: Profit

Is this after you have generated blobs with the modified bootloader ?

i.e. after you have generated your blobs with the androidroot.mobi bootloader you flash standard 4.13 b/l and then afterwards 4.23 ?
 

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  • 39
    The AndroidRoot.Mobi Team is proud to present Flatline: Nvflash for Nexus 7 & Nexus 7 3G (2012)

    This release allows generating nvflash blobs for your specific device, making your device unbrickable as long as you have a copy of the blobs.
    As a brand new feature, it will also enable wifi and upload a copy of the blob to androidroot's server. Later, a solution will be released to retrieve the blobs from the server if you ever loose them.

    https://www.androidroot.mobi/pages/guides/tegra3-guide-nvflash-jellybean/

    Credit goes to the AndroidRoot.Mobi team:
    Bumble-Bee (Apache14), IEF, kmdm, lilstevie & RaYmAn.
    4
    I know how to install the 4.23 bootloader...

    Step 1: Get into fastboot by... Well if you don't know how to get into fastboot then why did you do this???
    Step 2: Get the unmodified 4.13 bootloader (attached as 413bl.img ) and flash it by using" fastboot flash bootloader 413bl.IMG"
    Step 3: Reboot into bootloader using volume keys
    Step 4: Flash the 4.23 bootloader (attached as bootloader-grouper-4.23.img )
    Step 5: Reboot
    Step 6: ???
    Step 7: Profit
    2
    Ah yes! This makes updating the bootloader a less scary procedure. (It happened to me and I had to send an RMA request. Fortunately, they accepted it.) I do have a question. Are the blobs hardware specific for the Nexus 7? (Flashing someone's Nexus 7 dump to mine.)

    Sent from my Nexus 7 using xda app-developers app

    The blobs are device-specific. They will only works on your particular device and no one elses.
    Otherwise, we would have just released pre-made blobs :)
    2
    Little question:

    There's way to obtain device-specific key (SBK) after hard brick? like site with algorithm used in key generation, or something like that?

    If it was possible, wheelie would have done just that automatically. Unfortunately, the algorithm isn't known.
    2
    Or is there still a way we can royally f**k up the nexus softwarewise?

    Software wise, generally no. Once you have generated your nvflash blobs the only way to truly destroy your n7 is by doing something that breaks hardware, this can be done by software though if for instance you ignore thermal monitoring and overclock it to the point where the CPU hits thermal runaway, but that is a common sense thing to watch out for when overclocking. As long as no physical hardware damage is done though (and I'm talking on a component level here) it is virtually unbrickable as long as you have wheelie blobs generated with flatline.