I have found this has happened to others before me. all of a sudden my screen goes blank. it lit up, but its black. I hit the sleep button it turns off. I hit the home button and it lights up black again. I then try to reset it and the screen turns off and the starts vibrating non stop until it dies!! (for about 40 minutes, my baattery was only 30% charged.) I plug my phone in now and nothing happens what so ever. It's now a $700 paper weight!!