I found myself keeping my phone in my back pocket seems to be causing the issue. It seems the phone is bending. I have to bend my phone the opposite way over my knee. Put your phone screen up with the middle of the phone on your knee. Push down on the top and bottom of your phone quite firmly but not enough to break it of course and slide it around a little bit while pushing down. Works every time for me. There must be a connection that comes loose from sitting on the phone.