Macbook Pro not starting up, black screen

I was using my MacBook Pro and the screen went black. I forced it to shut down and now it isn’t functioning properly. When I press the power button the boot sound comes on 1/2 way and then nothing happens. Screen stays black. I tried cleaning out the vents, the holding down option command P R, the holding down the S, the holding down the shift,……nothing is working. Please help. Thank you in advance!