I have this problem every so often but today my phone died and I didn't have my charger with me to save it from turning off. Got home out it on charge. Went to turn it on, it turned on fine but the screen is black. I have pressed the power button loads of times. Battery reset Where u press the volume down button and power button together and I have tried all the other tricks I do to get it to turn on but nothing works. Can anybody help. I'm going to wait till morning to see if it sorts itself out