Phone bricked for no reason. No warning signs and metropcs no help

Yesterday my phone literally just turned off and won't turn back on. I have never had any problems with this phone and it has never been damaged. It has no water damage or anything and metropcs has the worst customer service I have ever experienced. They basically told me to just buy a new phone/that's your only option even after I told them it is still under warranty and I just need to know what steps to take and all I ever got was "I can help you buy a new phone". Sorry, so I need to know why it would just quit with zero symptoms before hand and no I did not mess with it. I'm not computer savvy enough to hack