Perhaps the unit should be taken in an Apple repair center, or an Apple Authorized
Service Provider; through an appointment for deeper diagnostics to see what may
be the cause. And a following repair estimate of costs; to replace hardware, etc.
If your Mac doesn't start up all the way - Apple Support
//support.apple.com/en-us/HT204156
If your Mac starts up to a blank screen - Apple Support
//support.apple.com/en-us/HT210905
Try to start up from macOS Recovery
"If your Mac seems to be turned on but the screen remains blank,
follow 'the appropriate steps' depending on whether you're using a
Mac with Apple silicon. If you're not sure, you can try it both ways."
IF at the end of these articles, there is no apparent remedy
the unit needs to see service support for advanced testing.
Contact us
IF the issue continues, contact Apple Support. (Blue text/link)
Genius Bar Reservation and Apple Support Options - Apple
//www.apple.com/retail/geniusbar/