[LG Optimus G Pro] nwdrifter:
First of i'd like to thank the community! I've ran in to numerous issues and have been graciously saved several times.

I'll start of by providing some context in to the issue.

original configuration:

Unlocked - T-Mobile US SIM

AT&T LG E980 factory tot 4.1.2 - flashed using LG Flashing Tool

Root - E980 Universal Root

Unlocked Bootloader - Freegee [Android Marketplace]

Installed Recovery TWRP v2.6 - Freegee [Android Marketplace]

Removed bloatware - AT&T Applications

So from this point the phone was working as expected. I spent hours configuring to my liking and decided to call it a night. Before I called it quits I decided to make a backup using TWRP. Backup took a really long time but it said successful. I left handset plugged in to charger overnight, roughly 6 hours of continuous charging. When I woke up I noticed the phone was in recovery mode. Touchscreen was also unresponsive. I held the power button to allow it to reboot and it rebooted me back to recovery. At this point I knew something was wrong. I attempted to re-install backup files made from previous night, this failed. The phone booted back to recovery. I then installing some zip files I had pre-loaded on to the external SD card, this was CM10.1 and gapps files for E980. I tried this out a few days ago and it was working fine. I decided lets try installing this and see what happens. Install was successful and rebooted. The phone boots back in to recovery. At this point I'm really frustrated. I checked the memory card by running through the TWRP menu. I noticed the file sizes were unchanged but the files were not displayed on both in/ext memory. I decided to finally restore again by using LG Flashing Tool. This by the way has saved my a$$ numerous times. So the one thing I would note, at the 85% when the phone reboots I noticed there was an error, an error I've never seen before. It was a picture of sync icon (large) and android man on top of it and text that said "error 0x123456" I didn't note the exact string. I let it go and monitored the flashing tool, somewhere around 93-95% it rebooted again in to the normal boot sequence. Viola my phone is back to where I started.

So here's some of the questions I had:

How did I end up in the TWRP Recovery boot loop?

Why could I not see the files to install once in TWRP?

Why did TWRP continuously boot back in to recovery mode after successful install of restore?

Why did TWRP continuously boot back in to recovery mode after successful install of CM10.1/gapps zip?

Has anyone seen the LG Flashing Tool error I described above and does anyone have an explanation as to what happened?

Here's my theory on what happened...

My phone was on 4.1.2 as mentioned. I noticed a few times that there was a notification stating the phone had a OTA software update available. The first time I tried to update (already rooted and unlocked) the phone failed to update. The error cited that my phone was believed to be rooted. I paid no attention to this and decided to continue using. Later in the day I noticed the notification again, I opted to try again. The phone updated, or at least tried to. It kept booting in to TWRP Recovery. Nothing I could do could restore it, except flashing using the LG Tool. After experiencing this I knew to leave the OTA alone. I don't know if this is possible but somehow I think the OTA was pushed and forced through while I was sleeping allowing the phone to charge. This is the only time I've seen that behavior. Is that even possible???

Where am I now...?

Phone is restored, I opted to upgrade using the OTA before I start tinkering again. Maybe I won't mess with it at all and leave it alone at this point.