[Nexus 7 Q&A, Help & Troubleshooting] bftb0:
No. It means that for some strange reason, running a checksum program on the downloaded OTA file failed to produce the expected checksum. The most likely way this can happen is that the file is truncated - the download stopped short of the full file. Don't know why this is happening, but there you go. There could be other failure causes that are more rare, but it doesn't mean you are not "supposed" to have the OTA. It means that the download process is failing.

The *stock* recovery does a number of even more sophisticated checking than this; but it appears from your description that the recovery never even gets booted.

Yes and No. An unlocked bootloader causes no problems at all. ANY of the following CAN or WILL cause problems:

- attempting to run an OTA with a custom recovery installed instead of the stock recovery.

- having a modified boot partition (e.g. non-stock kernel, or slightly modified boot partition)

- having altered (or removed!) files in the /system partition that are targeted for patching.

- permissions changes performed by the installer script can cause root functionality to disappear

Not sure what you are asking here, but the basic answer is that if you stay on stock you can certainly apply OTAs easily. If you start altering things, you might or might not be able to apply an OTA; there are simply no guarantees.

[size=+1]OTAs are meant for stock installations - including a stock recovery. PERIOD. While it is possible that an OTA could succeed, it is unreasonable to have the expectation that it will do so.[/size]

I presume you are talking about the future here, as you said that you already did a factory reset at least twice. If you have subsequently added stuff back in, then I suppose you might be talking about the present tense.

But, yes - either TiBu or the Carbon app can be used along with a strategy where you simply back up the apps & data you are interested in, (plus any "flashable zips" that you used to customize your device in the first place), and you simply start from scratch with a factory install followed by re-rooting, and then restore your apps & data (using TiBu or Carbon).

One other thing you can do which is EASY is this: simply wait until a developer/ROM cook publishes a "Stock" flashable ROM based on the release that the OTA is upgrading to. Don't worry about the OTA, just wait a little bit. (These ROMs are already out for the WiFi-only model, BTW).

1) Take a backup as the first thing you do. It's easy and gives you some insurance.

2) Don't wipe (no "factory reset") - just install the Stock ROM over the top of your existing ROM.

that's it. If you were using a custom kernel, re-install it.

[size=+1]OTAs are meant for stock installations - including a stock recovery. PERIOD.[/size]

Interpret that as you desire. It is unreasonable for you to expect that you can diddle with your phone any way you please, and a patch install upgrade methodology will be robust in the faces of arbitrary changes on your part. You are the person creating the maze, not Google.

Moreover, it is your choice to take an upgrade - it's not mandatory. My guess is your tablet was quite pleasing to you before any OTAs started rolling out. Nobody is forcing you to do anything.

OK, one last thing. It is still possible that a manual OTA can succeed on your phone if it is lightly rooted - but there are no guarantees. The procedure does not require you to wait around until an OTA arrives on your phone, but it is not for the faint-hearted:

1) Download the appropriate Stock OTA File.

2) Re-install the stock recovery onto your tablet. You will have to dig it out of the Google full factory image for the version of the OS you are currently running. (available here)

fastboot flash recovery factory-4.2.1-recovery.img

3) Soft-boot into a custom recovery, e.g.

fastboot boot openrecovery-twrp-2.4.1.0-grouper.img

5) Using the command line and adb to communicate with the soft-booted recovery, create a recovery command file:

C:\myPCsux> adb push 6ece895ecb23.signed-nakasi-JDQ39-from-JOP40D.6ece895e.zip /cache/update.zip
C:\myPCsux> adb shell
# cd /cache/recovery
# cat > command
--update_package=/cache/update.zip
^D # ( that is a Control-D character )
# sync
# reboot recovery

This will either succeed or fail. Based on your comments though, you might just want to overflash a Stock-derived ROM over the top of your existing ROM (a "no-wipe" install).

[ROM][Factory Image][4.2.2] Nakasi -::- Odex, Deodex, Rooted -::- teshxx (02/14/13) <-- NOTE for WiFi (nakasi/grouper) ONLY

good luck with your tab.

Someone once said "Rooting is a lifestyle". There's some truth to that; it eats up your time. Perhaps it is not for you.