Why won't the screen turn on?

I've had my six for over a year now. It's been through !&&* and back. The front is very cracked, there's pieces of glass missing from the top and the bottom of the screen. My phone died at school, I attempted charging it and after two hours it still would not reboot. When I took it home, I left it to charge in an outlet for an hour. Still nothing. At this point, the screen wont even show me the image of a battery, letting me know that my phone was dead. I plugged it into my laptop, and my laptop then made the sound notifying me that my phone was plugged in and charging, but the screen is still unresponsive? Completely blacked out. Please help.