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2012 Nexus 7 Discussion Forums (1st Generation) => Nexus 7 Help => Topic started by: birdastrompgman on March 17, 2014, 12:24:05 AM

Title: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 17, 2014, 12:24:05 AM
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. (https://www.androidroot.mobi/pages/guides/tegra3-guide-nvflash-jellybean/).  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
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 17, 2014, 12:31:40 AM
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!

Quote
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
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 17, 2014, 07:04:23 AM
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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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 17, 2014, 10:07:12 AM
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.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 17, 2014, 04:57:16 PM
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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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 17, 2014, 07:01:21 PM
http://forum.xda-developers.com/showthread.php?t=2244413

Someone got out of apx.

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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 17, 2014, 11:34:52 PM
[url]http://forum.xda-developers.com/showthread.php?t=2244413[/url] ([url]http://forum.xda-developers.com/showthread.php?t=2244413[/url])

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.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 18, 2014, 10:46:23 PM
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.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 19, 2014, 01:15:08 PM
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!
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 19, 2014, 01:35:25 PM
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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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 19, 2014, 04:31:38 PM
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.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 19, 2014, 05:19:00 PM
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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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 19, 2014, 06:37:50 PM
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.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 19, 2014, 07:41:00 PM
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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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 20, 2014, 08:21:38 AM
Well, mine is, or was a 32 GB model.  I guess I'll be buying a 2013 model by the end of the week.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 20, 2014, 02:30:48 PM
http://www.powerbookmedic.com/Google-Nexus-7-Service-Parts-for-Repair-p-1-c-709.html

34.95$ for a 16 GB main board...

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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 20, 2014, 10:40:01 PM
Thanks!  I ordered a 32GB motherboard for $50 with free shipping.  I doubt I'd have come up with that idea, so I owe you an ice cream or lunch if we ever meet.  I'm still going to give the broken N7 to my son, but with the replacement motherboard.  I ordered myself a refurbished N7 (2012) for myself for $129.  It's hard to justify another $100 for the Snapdragon CPU.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 23, 2014, 09:43:31 PM
Well, I stumbled onto a refurbished scratch and dent 16GB 2013 N7 for $185, so I'll probably send back the 2012 N7 and keep the newer one - or maybe I'll keep both.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 26, 2014, 02:49:29 PM
The replacement 2012 N7 came in.  I unlocked the bootloader, flashed the flatline_grouper.img recovery, and flashed the AndroidRoot BL bootloader.  Then I made the blob.bin bootloader image,

I can now get in and out of APX mode using wheelie, but I can't attain nvflash status, because the "wheelie -b -blob.bin" command doesn't get me into the bootloader from APX mode.  It says it completed sending the bootloader, and my device should be ready for nvflash, but the Nexus 7 stops at the Google and unlocked lock screen rather than continue to the bootloader.  Nvflash  commands other than nvflash -h return "unknown command" messages.

Could the problem be that the N7 came with Android 4.2.1 and its newer bootloader?  I flashed back to 4.1.2, prior to changing the recovery and bootloader, since nvflash is set up for the 4.1.3 bootloader
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 26, 2014, 04:16:36 PM
You've gone beyond me.. Did you reboot after flashing the boot loader? Seems it is written to a staging area and doesn't install until reboot maybe. Xda is a pain to navigate, but there is more posting on this issue.

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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 26, 2014, 06:47:21 PM
Yes, I rebooted after each step, and repeated each of them.  I also tried each volume button position when doing the wheelie command, in case it might help boot into the bootloader.

I started a thread in the Nexus 7 help forum.  Searched for APX and nvflash attained, no useful hits and lots of bricked N7s in APX from peeps who didn't make bootloader backups.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: matt on March 27, 2014, 03:32:45 PM
http://forum.xda-developers.com/showthread.php?t=2455927&__utma=248941774.1520026655.1395953394.1395953394.1395953394.1&__utmb=248941774.2.10.1395953394&__utmc=248941774&__utmx=-&__utmz=248941774.1395953394.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)&__utmv=-&__utmk=34128034

I think this is the dev site, looks risky to me. Bad bootloaders in some factory images! Maybe this will get out of pre beta someday.

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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 27, 2014, 06:12:31 PM
Thanks.  That's a new link for me.  I got my original bricked N7 running with the $50 32 GB motherboard replacement.  It was touch and go, as the unit was completely and utterly dead after the PCBectomy.  I left it charging all night, and it was still dead this morning.  I was writing a message to the seller (who has a 100% eBay reputation), when I unplugged and replugged the charger cord, and saw the battery icon go on.  An hour later, it booted into 4.4.2.  It's now rooted, and will go to my son, as I promised I'd give it to him.

Meanwhile, unit 2 is my test mule, and it's rooted and running 4.1.2, but it's not entering nvflash.  I just flashed CWM recovery, so maybe it'll enter nvflash with the new recovery replacing the flatline recovery.
Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 28, 2014, 10:24:00 PM
I reflashed the OEM bootloader and CWM recovery. Still no progress to nvflash.

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Title: Re: N7 (2012) stuck in APX mode with corrupted bootloader
Post by: birdastrompgman on March 29, 2014, 10:41:06 AM
I took my other 2012 N7 down to 4.1.2, reflashed the bootloader, went through the blob generating procedure, and couldn't attain nvflash with that device, either.