Try resetting the SMC http://support.apple.com/kb/ht3964
1 Choose Apple menu > Shut Down.
2 After your Mac shuts down, press Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds.
3 If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
4 Release all keys.
5 Press the power button again to turn on your Mac.
Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379
1. Shut down the computer.
2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Press and hold the Command-Option-P-R keys.
4. Turn on the computer.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.
Your computer's PRAM and the NVRAM are reset to the default values. The clock settings may be reset to a default date on some models.
Try resetting the SMC http://support.apple.com/kb/ht3964
1 Choose Apple menu > Shut Down.
2 After your Mac shuts down, press Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds.
3 If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
4 Release all keys.
5 Press the power button again to turn on your Mac.
Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379
1. Shut down the computer.
2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Press and hold the Command-Option-P-R keys.
4. Turn on the computer.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.
Your computer's PRAM and the NVRAM are reset to the default values. The clock settings may be reset to a default date on some models.
My Mac turns off after updating?
