From previous posts, looks like OP has a 2013 MBPro.
First, try an SMC reset -
https://support.apple.com/en-us/HT201295
When you have done that SMC reset, and you are at the last step when you can press the power button, try an NVRAM reset, too:
Press and release the power button, then immediately press and hold Option-Command-p-r.
Keep holding those keys. You should hear a boot chime. Keep holding the same 4 keys until you hear the boot chime 2 more times, then release the keys to let it try to boot normally.
If the screen remains black, shine a light into the screen, from various angles, just to try to see menus, or icons, or anything on the screen, even if it's very dim.