Repairing Mac Desktop Auto shutdown

Depending on type of Mac Desktop and year built, two things can be done at this point.

1. Shutdown your Mac Desktop by holding the power button for 5 seconds.

2. unplug the power cable and leave it unplugged for 15 seconds.

3. Plug back the power cable and turn on the computer after 5 seconds.

4. So far, what you have done is reset your SMC already.

5. Now as soon as you turn on the system, hold command + option + P + R until you hear the second restart beep.

6. Release the buttons.

7. You have just reset PRAM as well and your computer must be working without any shutdown.

8. Keep in mind that you may need to configure some of computer basic settings that memorized on PRAM before reset process.

Good Luck.