Had some issues with an iPhone which were similar to this case. Replaced one screen for a customer of mine after she broke it. She brought it back cause it was black.. I assumed I just had a bad batch of screens. Checked seating of battery and reseated and checked connections to LCD. I have now burned out two screens because of heat. Never thought to check heat. Just happened to be charging it for her and noticed it was very hot. Gets hot at the upper most part of the logic board on left side very near the camera. Replacing the logic board was the remember but now I have a board that seems to want to continually overheat to the point where battery charge declines rapidly.
Moral of the story is to check heats. What caused it? Probably something I did ..