Issue after flashing 10g Stock - Black Screen

Hi guys. I have a factory refurbished AT&T E980 that had stock 4.2.2 on it when I got it. Assuming it was the last OTA that was pushed out. I attempted to downgrade to 10g because I was still learning the recovery options for this phone. I've since flashed most of the available JB builds with similiar results. From off, the phone will show the AT&T logo for a few seconds, then go to a black screen for several seconds. Then I have to hit the power button twice to bring up the home screen. There is no boot animation, but you can hear the accompanying sound. I seemingly cannot get any roms to boot, other than stock, as they all hang at a black screen, even after wiping/factory reset. I also cannot get any variants of recoveries to work, other than the CWM packaged with GPro Recovery. The TWRP included with that only shows a black screen with the back and menu buttons lit up, and the home button cycling through colors.
I've searched through the forums and haven't seen anyone experiencing this issue. My only clue to the problem is reading something about another LG phone that, once refurbished, came with updated display drivers that caused a similar issue. Here.

Any insight would be appreciated.