- Loudly fan but no apps is running
- Battery showing 0% charged in "Energy Saver" in "System Preferences"
You may try to reset the SMC, here is the instruction for MacBook Air
- Shutdown your MacBook Air (go to the Apple menu and choose “Shut Down…”).
- Make sure your MacBook Air has external power. Connect the power adaptor, if it isn’t already.
- Using the Air’s built-in keyboard (not a plug in keyboard or bluetooth keyboard), of the left hand side of the keyboard press Control-Shift-Option and on the top right of the keyboard, the power key at the same time.
- Release all the keys at the same time.
- Press the power key to start the computer.