Apple provides instructions for reseting System Management Controllers. For Macbook users (including Macbook Pro and Macbook Air users) with non-removable batteries, which are nearly all Macbooks from 2009 foward, Apple directs to press and hold Shift-Control-Option keys on the left side of the keyboard and the power button for ten seconds, then release. Then press the power button again.
If this does not work, Apple states users should take the Macbook back to Apple for service. What should a user without an Apple store nearby do? What about users whose Macbooks are out of warranty? The answer is simple. Remove the battery and drain the power from the capacitors on the mainboard.
Simply do the following:
- Unplug the Macbook.
- Turn the Macbook over.
- Remove the (usually ten) screws from the bottom of the Macbook.
- Remove the bottom cover.
- Gently pull straight up on the battery connector to disconnect it from the mainboard.
- Gently open the Macbook’s display part way and rest the Macbook on its side.
- Press and hold the power button for 5 seconds.
- (Optional) Wait 30 minutes.
- Put the Macbook upside down again.
- Reconnect the battery.
- Replace the bottom cover.
- Replace the screws.
- Plug in the Macbook.
- Press the power button.