If I power the phone on and set it down, it stays on. If I go ahead and use it, say to send a message, and set it down, it immediately powers off. I have to push the power button and start it again. I can tap it and jiggle it around when it is on and it doesn't power off, so doesn't seem to be a wire or battery problem. Is there a setting I am missing? Some kind of security setting? What else could be wrong?