[G2 Android Development] david black:
I was in the same situation, but returned my phone to Sprint after using the TOT method and blaming the brick on the radio update. They accepted it and gave me a new device.

Looking back, I have thought through a method that should work, but will require patience and speed.

First backup your efs copies to a computer, flash drive, another phone, otg drive etc. Don't lose them or do anything to compromise them.

Since you don't have a custom recovery, you'll need to root first. I found that when my phone would bootloop after no more than a minute of use I didn't have a lot of time to make decisions.

Get your root application ready on your PC. Boot the device into it's stock recovery (you should have one if you TOT'd it). From there, wipe cache, factory reset and the whole nine yards. If adb sideload will work from the stock recovery, send the FreeGee apk to the phone. I believe that app will allow you to restore using .img files. PM me if you can't get the apk.

Once the above is done, you're set to perform the "first boot" and root. Remember to work quickly. Skip all that accessibility and activation stuff and go immediately into settings. Scroll to the bottom and click about phone. Then click software and click the heck out of build number. Immediately go back to the system settings and in to developer options. Enable USB debugging and plug your phone into the USB cable that should be connected to your PC. Run the root app. If it's successful and you still have some time before the pending bootloop, go to display settings and disable the lock screen (this buys a little more time on the following boots because my device wouldn't respond to touch and when the lock screen timed out, I would have to start from the very beginning due to never getting past the lock screen). If you still have time before the loop, enable airplane mode.

After a successful root and hopefully a custom recovery install, copy your efs images on to your phone. I always have to use my OTG flash drive to successfully move a file for some reason. Try restoring just the efs using TWRP. If it fails, uncheck the md5 options in advanced settings and maybe try mounting the system (not sure if the final piece will help, but when it's bricked you really have nothing to lose).

On the next boot use FreeGee to restore your efs if your custom recovery wouldn't do it. Remember to work fast and hopefully you have the lockscreen disabled so you can get into the phone. Also, if you have time, set the screen timeout to 5+ minutes and enable unknown sources in security settings. Disable the option for Google to check for malicious apk's too. You don't have time for them to attempt to check anything.

I think in your situation, it's great that you have your efs (plus a full nandroid) backed up for the exact device you're receiving. The primary key is speed and then patience is a close second.

Once you have the device rooted and TWRP installed, you shouldn't have any issues. You seem to know enough about this phone + Android to get through this.

I haven't read any posts beyond your original one that I quoted, so if someone has given you good instructions or your problem is solved, hopefully this helps add the collection of how to unbrick these tricky G2's.