Originally Posted by raptir
If you worked hard to get root on a Nexus device you did something wrong. It should be as simple as unlocking the bootloader (already done), flashing a custom recovery (already done), and flashing the SuperSU ZIP file (this is the only step you'd need to repeat).
That said, doing a factory reset should not remove root. Even if it does, it would be restored when you restored your rooted Nandroid.
Easy for an expert. I'm a newbie. I used the WUGfresh toolkit and it took multiple frustratng attempts and forever for it to finally
download the correct adb drivers that would recognize the Nexus 7. Then all went smoothly.
But back to the present. I'm all fine now (till the next time the Nexus 7 crashes on me). For other newbies like me
who run into this problem and need simple instructions here is what I did.
The first time this crash with the boot stuck on the X screen happened, going to the recovery screen (Power button + Volume up simultaneously) showed me the android on his back with a red triangle. Pressing power button and briefly volume up gave me the option to reset the tablet without removing root. Because I was traveling and did not have my TWRP backups with me (they were on my laptop 1,000 miles away) this removed all my data and I had to re-install all my apps and everything again.
The second time this happened, the recovery screen took me to the TWRP recovery screen. TWRP recovery had apparently survived the crash. I needed to save my data before reseting the tablet again. By trial and error I discovered that the TWRP menu has under the Advanced Tab a file manager. also discovered that if you connect a flash device to the tablet's usb port the TWRP file manager could read and write to it (!!!) in a folder called usb-otg (but not to my windows laptop). I copied what I wanted to save to the flash drive. Then I used the "wipe" tool to return the tablet to android.
I installed a free app, Recovery Manager, to reinstall TWRP recovery. Copied my previous TWRP nandroid backup to the tablet and restored everything as it was.
Easy as pie if you know how. I hope this helps some other befuddled user.
sfhub and raptir: Do you know what can be done to prevent this from happening again? Could Google Play being conected to in Europe after it was used to being to conected to in the US cause the problem? Both times the crashes happened shortly after I used the tablet in Europe and the the second time after I used it for the first time in the US.