OMG! Thank you, thank you. Picked up a refurb Nexus 7 (2012) from Walmart, and it had 4.2.1 on it. The tablet successfully and happily began installing bought apps from the play store. Then the dreaded update screen arrived, would you like to upgrade to 4.3. Being the neophyte with the tablet and trusting google, the reply was "yes; install' It went through the entire reboot, install, upto 100 percent, then 'ERROR'. Now the tablet was soft bricked. No help from Google tech support.
Given pat answeres to restore to factory from recovery, and this did not work. Trusted the Walmart return/replace policy and got a silly refund card. Back online, order another one and have it delivered.
This time after booting up and not taking time to install any new apps, checked for updates to os. Yep, 'Update available, please install" "ok" and it happens again: Soft Brick. This time I was prepared, I had researched and found your wonderful tool.
Installed this to my Macbook Pro, connected the softbricked tablet, went through the procedures:
1. unlock device (success)
2. Install CMW (success - though probably unnecessary)
3. Restore factory image (success)
Now the factory image installs 4.4 and boots successfully!
The tablet after connecting to the internet and my google account now informs me there is an update to 4.4.2 ok to install? I answer yes!!
Success!! its a good update.
So there seems to be some sort of update bug going from 4.2.1 to higher via the normal Google update route, but your tool allows us to bypass this and fix the tablet.
Thankyou
As for why I am posting all these details? Just in case someone else runs into this problem and would like to avoid the issue, I thought I would document it here.
BTW, one question, at the end, my tablet is still unlocked. this is ok, right? (unless I need to return it for some repair/warranty work), but given the lack of real support from google or Walmart at this point, I expect that I am the tech support person.
BTW, this was all just to give a gift to my spouse for Christmas (what a hassle) If I hadn't heard such good comments about the device here on XDA, I probably would have given up a lot earlier.