Screen won't turn on

I tried to turn on my tablet and the screen is black. I tried to hold the power button down for 30seconds & turn on, no luck. Tried to hold the power button and the volume up simultaneously for 15 seconds & turn on, no luck. I tried to then push the power button down three times back to back, no luck. I push the Windows home screen button on the bottom and feel the touch screen working but the screen stays black. Anyone no what else I can try?