Reset the System Management Controller
Power-related settings can be controlled by the System Management Controller (SMC). A reset of the SMC may be needed if there are issues with the following:
- Powering on
- Waking up after putting to sleep
- Charging or holding charge
Click the Apple icon in the top right corner and select Shut Down.
Plug in the MagSafe or USB-C power adapter.
Press Shift + Control + Option and the power button at the same time. Hold for a few seconds.
Release all keys, then press the power button again to restart the Mac.
The LED on MagSafe power adapters might change states or temporarily turn off when resetting the SMC.