So, here's what happened. I'd overlooked a rubber gasket that was meant to keep the charging port from shorting on the rest of the frame. As such, it was getting shorted. I replaced the gasket and now everything is fine! It still shorts from time to time, but that's because I don't have adhesive between the LCD and glass. I will get that as soon as I can, but in the meantime, I need to keep pressure on the phone when I'm not using it. Hopefully someone else can learn from this!