Doesn’t turn on

Disconnect any and all external drive and connect to charger. Attempt to startup and immediately hold Command + v. This is Verbose mode. A Terminal type screen will hopefully load and eventual ( if successful ) Log in Screen. If successful let it run that way for 5 - 7 minutes and try restarting in Normal mode.

Should nothing work - contact Apple for Repairs

Plug into charger and hold the Power Button for 10 seconds release and try again to startup. No luck preform a SMC Reset

Reset the NVRAM