I had the same problem and I removed the logic board and the touch sensor need to be secured with a piece of rubber. I watched a youtube video on it https://www.youtube.com/watch?v=8mmmfk0Ag1Q and this helped a lot. I did this and have not had any problems since. I hope this helps. If your phone is under warranty take it to an Apple store and they will replace or fix it. If it's not like mine, I saved myself couple hundred bucks for the repair or new phone.