You could try NVRAM reset and hold 4-keys down until Mac chimes, at least 2
or 3 times. (This may not work on newer model Macs; but should make 'restart
chime' sound at least once.)
• Reset NVRAM or PRAM on your Mac - Apple Support
https://support.apple.com/en-us/HT204063
Shut down your Mac, then turn it On and immediately press & hold these
Four keys, together: Option, Command, P, and R. You can release the keys
after about 20 seconds, during which your Mac might appear to restart.
(The matter of timing to make above work correctly, may require more than
on try, to initiate the NVRAM reset. Some Macs make no sound, on restart.)
This may help; if an actual reset was done. False starts may have no yield.
The other reset might needed, should display issue be power related; so
try & reset the SMC (System Management Controller) as that may help.
Take care & good luck!🌤🎣
