So I finished a Calculus quiz and left the classroom. As I was leaving the classroom I wanted to check my phone to see what time it was. When I pressed the power button I was greeted by the NOKIA black startup screen. I put the phone back in my pocket, figuring that it just restarted or something. My phone has been off ever since. It won't respond to any soft resets or the power button. I plugged it in, still nothing. The power was around 90 percent when it crashed so I'm not sure what the problem is. Please help?