Unexpected shutdown during Software update
Does anyone know how to recover from an unexpected shutdown during Software installation? MacBook Pro won't restart. Keeps shutting down during installation.
MacBook Pro 13", OS X 10.11
Try booting into Safe Mode.
It is possible you could have a failing hard drive.
See if you can run the Apple Hardware Test or Apple Diagnostics depending on the age of your computer.
If the computer is out of warranty then you can still take it to an Apple Store to be evaluated for free.