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Root Nexus 7 failing to boot into Android

H

HarvA

Lurker
Hi all,

I have an issue with a Nexus 7 2012 Wifi tablet not booting into Android.
The issue occurred after the tablet prompted the user to install an Android OS update. The user went through with the update, and seemingly the update failed at some point.


  • The bootloader is locked, and USB debugging is disabled. The OS version etc. are also completely stock.

  • The tablet cannot load Android up. It simply sits with the 'Google' loading screen forever.
    • Because Android won't load up I CANNOT enable USB debugging.

  • The tablet is able to get into the bootloader menu (by holding down the 'Power' and 'Volume Up' buttons).
    • Selecting 'Recovery mode' displays "Booting failed".
    • Selecting 'Restart bootloader' causes the device to restart, however it displays a black screen and does not progress any further. (I know the device restarts instead of powering off because the device is connected to my Windows PC, and during the reboot the Windows 'disconnect' and 'reconnect' noises play).

  • The information shown in the bottom-left corner of the bootloader screen shows:
"FASTBOOT MODE
PRODUCT NAME - grouper
VARIANT - grouper
HW VERSION - ER3
BOOTLOADER VERSION - 4.23
BASEBAND VERSION - N/A
SERIAL NUMBER - [SerialNumber]
SIGNING - not defined yet
LOCK STATE - LOCKED"

​
  • I have installed the Android SDK, and have also installed the correct USB driver for the tablet. I can see mention of 'Android Bootloader Interface' within Device Manager.

  • After opening a command prompt and navigating to 'C:\Users\[Username]\AppData\Local\Android\android-sdk\platform-tools', I have run the following commands:
    • 'adb devices'. This displays "List of devices attached", and does NOT then list any devices at all. I believe this is because USB debugging is not enabled.
    • 'fastboot devices'. This displays the serial number of the tablet and then "fastboot" i.e. "[AndroidSerialNumber] fastboot".
    • 'fastboot oem unlock'. This causes the tablet to ask if I want to unlock the bootloader. If I select the option to unlock it, the device reboots, then displays a black screen (just as when selecting 'Restart bootloader', as mentioned above).

  • I have also downloaded the Factory Image for the tablet, however when running the 'flash-all' script, the command prompt that appears shows "FAILED: Bootloader locked"

I suspect that the update removed several crucial software components from the device, such as the 'recovery' and 'boot' components, and then the update failed before it replaced them, however I'm by no means an Android expert and haven't ever looked into this sort of thing before today! I'm guessing at this point that the device is completely bricked, but figured I'd ask on here before giving up on it.

If any of you are able to figure out how to fix this I will give you praise beyond your wildest dreams!
 
Hey HarvA, me again :).

First off, I'd like to thank you for providing such a detailed and rich set of information about your issue (you don't know how rare that is ;) :p) :thumbup: :).

It actually sounds like you've covered all of the bases one would normally try...and your's is, unfortunately not the only first-gen N7 we've seen that the bootloader unlock (fastboot oem unlock) is failing on :(. [there are probably a couple other fairly recent threads in this all-things-root area that you might see that look similar to your issue].

http://androidforums.com/nexus-7-gen1-2012-all-things-root/867400-stuck-in-bootloader-no-os-o_o.html

Not sure what else to suggest at this point other than asking if you are using a USB 3.0 port for communicating with the device? If that's not the case, then possibly try another USB cable and/or another computer to rule-out a USB communication issue being the problem (although if you're getting to the point where your device is asking you for permission to unlock and you use the volume toggle to say "yes" and select it with the power button, that's probably not the case).

Anyway, that's all I got at this point...
 
Hi scary alien,

I'm sure I replied to this thread the other day, but I've just noticed it's not here. I'm guessing I must have clicked the 'Preview Post' button instead of 'Submit reply'. Anyway, thanks for your reply! I work in technical support for a software company so I know what it's like when people don't supply much information about a problem!

I've taken a look at the thread you linked to and a few others, but sadly it doesn't seem like anyone's been able to fix issue's similar to my own. I've tried another cable and USB 2.0 port, along with another computer, but the exact same behaviour was seen.

The tablet is still under warranty, but I doubt they'll have any more 2012 Nexus 7s in stock as this one was being sold as a clearance item. I also thought it'd be nice to just fix it myself really. It's not a total loss though, as at least I've learnt a lot about modifying Android devices. Plus, you never know, the place I bought it from might replace it with a newer Nexus 7! ;)

Thanks again for your support scary alien, it's genuinely appreciated :)
 
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