OS X Yosemite: If your battery won’t charge

If your battery on your portable Mac won’t charge, try one or more of these solutions:

• Reset the battery:
  If you have a Mac with a removable battery, remove it and install it again, to make sure it’s properly installed. Refer to the manual that came with your Mac for more information about properly installing the battery.
• Reset the SMC:
  Reset the System Management Controller (SMC), which controls how your Mac manages power. For more information, see the Apple Support article Intel-based Macs: Resetting the System Management Controller (SMC).
• Get your Mac serviced:
  If the battery still won’t charge, your Mac may need to be serviced. Take your Mac to your local Apple Store or contact AppleCare.