So I have the Galaxy S3 with Verizon, and I've had this one since about August 2013. I use the defender series otterbox to protect it. Last week my power button stopped working. I figured since I get my contract renews later this year I could live with it. However, today my phone vibrated once like I was getting a phone call, then it stopped. From then on, every 3 to 10 seconds it would just do a short vibrate. When I got out of class I checked my phone and found I couldn't even get the screen to come on using the button menu button. There were no lights flashing for any notification. Eventually the vibrating stopped, but as soon as I plugged my phone in to charge it the vibrations picked up again.