Mac book starts loading when turned on once loading it shuts down
Mac book shuts down when loading
Mac book shuts down when loading
Try an SMC reset:
How to reset the System Management Controller (SMC) on your Mac - Apple Support
Try starting up in SafeMode:
Use safe mode to isolate issues with your Mac - Apple Support
If those don't sort it then try reinstalling Mac OS:
I am not Able to get to the log on Screen
Mac book starts loading when turned on once loading it shuts down