I got a lumia 920 in exchange with my galaxy s3 from a guy through OLX. Now the phone is working but when it stays in idle or standby mode, it turns off by itself and I have to turn it on by pressing the power button for 10 seconds. This is very fraustrating. It does not goes off if the phone is working but once you keep the phone aside for 2,3 mins it goes off. Any suggestions? Any idea whats wrong with it? Plus I don't have any warranty. There is one more problem, the earpiece is not working while mic is working fine. And the camera has a lot of dust inside so its taking poor pictures. Front camera is flawless. Battery timing and other stuff is fine though. Please help. I'm new and windows experience has improved so well but this problem is really weird.