N7 (2012) stuck in APX mode with corrupted bootloader

[birdastrompgman]

My N7 wasn't responding in an app, so I powered it off.  Since then, it won't power back up.  I've tried holding the power button for more than 60 seconds, and I've tried powering it on into Recovery with the  power and volume buttons, unsuccessfully. 

I hooked it up to my PC and discovered I can put it in APX mode by pushing the power button.  The N7 gives no visible sign of turning on, but Win7 sees it as an APX device when I toggle the power button.

Apparently my Bootloader is corrupted, as the only repeatable method of entering APX mode is by erasing the bootloader.  The only way to fix it is to find a version of NVFlash for the N7 and reflash my bootloader, per this discussion..  I'll need some time to figure out how to recover my device.

N7 (2012), rooted, running Android 4.4.2. Out of warranty, of course.

I anyone has experience with this, or understands what steps I need to take, please tell me in this thread, or direct me to where this has been discussed/fixed.  TIA.

Best

[birdastrompgman]

If any N7 (2012) owner is willing to make a set of the needed img files from the previous link for me to restore my N7, I'd greatly appreciate your help!

For Nexus 7, we recommend backing up the following partitions:
$ nvflash --resume --read 5 eks.img
$ nvflash --resume --read 13 factory-config.img
$ nvflash --resume --read 14 mda.img

[matt]

From what I'm seeing, the blob files need to be created by the original device.

http://forum.xda-developers.com/showthread.php?t=1879228

Hard brick, damn.

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[birdastrompgman]

It's a bummer, for sure.  I think I can reflash the bootloader, and use fastboot commands to rebuild the firmware/software.  I have nothing to lose.

[matt]

Looks like dhsub is the Qualcomm driver for the 2013. Some talk of JTAG repair, soldering to motherboard. No solutions yet.

I'm thinking the memory got corrupted, when flashing a ROM from working fastboot, the nands must be reformatted and bad blocks logged.

If the hynix chips are going, you might find one with a broken screen and swap the main board.

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[matt]

http://forum.xda-developers.com/showthread.php?t=2244413

Someone got out of apx.

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[birdastrompgman]

http://forum.xda-developers.com/showthread.php?t=2244413

Someone got out of apx.

Sent from my Nexus 7 using Tapatalk

Info in that link (recovery reboot) didn't work for me.  I'll be home tomorrow, and hope to tackle the bootloader reflash then.

[birdastrompgman]

I'm going to generate my blob files from my stepdaughter's N7 [2012].  I'll downgrade its OS to Android 4.1.2, since the NVFlash bootloader image is 4.1.3 (it's running 4.4.2 currently).  Hopefully, I'll be able to report some progress tomorrow.  I'm backing up her data right now.

[birdastrompgman]

Ouch!  Reflashing the blob.bin bootloader failed because my chip UIDs are different between the two N7s.  Unless the chip UID is stored unencrypted in open view (highly unlikely in a binary file), I'm hosed.

All I  can say, guys, is make your blob files now, before you find yourselves in my situation!

[matt]

What I'm wondering, is the root cause. Static discharge to the USB port, cosmic rays or em pulse, or faulty chips? If the latter, might cut your losses and part out. The former, wait for a hacked nvflash that doesn't use so much security.


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[birdastrompgman]

My WAG is a cosmic ray glitch.  I wasn't doing anything unusual,  not walking in wool socks, not near loudspeakers or magnets, didn't drop it, etc.

My son dropped his 8GB N7 (2012) and cracked its screen.  I guess that'll be the best use for the parts.

[matt]

I'm leaning to some bad chips in the production line. The units RMA'd to Asus for this condition coming back with new main boards. (Left out solar flare)

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[birdastrompgman]

I purchased the N7 1 March 2013, so it died barely 15 days past the warranty expiration.  If there are a lot of units being returned with this problem, and motherboards are being replaced, I'll buy the bad chip theory.  It might also explain the $213 repair estimate I received from Asus for what I thought was a software installation.

[matt]

The bad units seem to be a small percentage, and perhaps only the 16gb. Waiting for mine to bite the dust, lol.

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[birdastrompgman]

Well, mine is, or was a 32 GB model.  I guess I'll be buying a 2013 model by the end of the week.