Black screen on power up
I have the same issue... I tried external display also, not working.
Check if you hear fans or see the light turn on at the front
It could be the integrated graphics,
send a video of it powering on
Try connecting it to power and see if it turns on, click the CAPS key to see if it turns on. If not then it could be a logic board issue, as well have you gotten any repairs done to it recently?