Crashed and now only white light blinking
Have you tried holding down the power button until the light goes out completely (10 seconds or longer)?  Then push the power button again and see if it boots.

You can try to reset the NVRAM (holding down CommandOption P and R at boot-up) and the SMC (if NVRAM doesn't work).

See https://support.apple.com/en-us/HT204063 and https://support.apple.com/en-us/HT201295.