LCD won't light up or scrolls green lines - what's wrong?

Back story on my Samsung Galaxy S4 i337M:

When I got the phone it had a broken LCD, so I refurbished my own glass/LCD combo with LOCA, and put it into the old bezel frame. The LCD wasn't adhered perfectly square onto the glass, so it tends to lift around the top, but I solved that issue by putting on a case that covers the edge of the glass.

That worked just fine for about a month. I reached into my pocket to check my phone, hit the power button, and no LCD light up - just the softkeys. I know the phone is still powered up normally because hitting the lock button lights up or shuts off the softkeys every time.

The first time it happened, I was able to get the LCD working again just by hitting the lock key over and over again, but since then has not been so easy. A battery pull seemed to solve the issue a few times, but one battery pull resulted in green lines scrolling down the screen. It's at the point now where most times a battery pull won't even solve my problem.

My LCD is not damaged. I checked very well. I even scrubbed the LCD flex where it plugs into the logic board, thinking maybe some LOCA leaked into the case. The logic board and case are totally LOCA-free, new battery didn't work.

Please help! Not sure where to go besides replacing the LCD, but I'd like to avoid that cost.

Thanks in advance!