I had my phone charging while it was on and using it. It powered it self down and now wont restart. i tried charging the battery and when its connected to the wall the four dedicated buttons flash. i took out battery and allowed phone/battery to cool then tried to restart, with same results. I had tried different outlets throughout house. also plugged it into the PC to see if it would start charging but no go. Any ideas before i got to the repair store tomorrow?