Touchscreen failing after minutes

Ok so I was asked to replace the screen and missing home button on a 6 plus, it was in a bad way and only part of the screen showed anything and the touch was not working, I replaced the screen and home button and tested as best I could as the phone was trying to verify an update but the accessibility dot did work and move about, the client took it home and got the update the the welcome screen when the touch stopped working, they brought it round and I refitted the screen checking it's fully connected and it works again for a few minutes then stops, I disconnected everything again and examined the connections and they look fine, when I refitted again it works but I noticed the shielding just down from the connections is getting very hot, is this a sign of damage from the original drop or is it possible the screen or home button is causing the issue?