Chosen Solution
iPad 6 brought to me with a broken digitizer and also with a home button that was torn off. Digitizer replaced with a new home button flex cable. Everything worked well and I sent it back to the owner. Next day I get a message that the LCD has gone grey with lines through it. I took the iPad back and started looking it over again. I realized that the flex cable from the home button was getting fairly hot. Could this be the reason the LCD stops working properly? Or has Apple done something to make third party home button repairs impossible. I can’t find anything regarding an over heating home button flex cable. I did order two new ones but have to wait for them.
If it gets hot usually means something is shorted inside, a replacement hardware issue is quite likely. Shorts can cause a number different symptoms. I find it a bit hard it can cause a screen fault as you described, but you can verify quite simple if the two things are directly connected simply by booting with home button disconnected.
