I have an idea what it might be but you will probably have to wait for Sprint to look at it so you don't void the warranty or insurance. There's two ribbon cables that hook into the board, one for the digitizer and one for the actual screen. The cable for the screen may have gotten loose and may not have a good connection. I've seen this happen before on another phone I had that Sprints Service Center looked at before. Just wait till they open and take it back to them and make sure when your there that the phone works correctly. And by the way the phone rebooting on its own happened to me once on Sat and never happened since so it may have just been a fluke. Sorry to hear about your problems hope it gets fixed soon for ya
