Remove the battery ASAP before any further damage can happen.
https://www.ifixit.com/Answers/View/36763/My+MacBook+battery+is+swelling.+Should +I+worry
2 replies
Your battery is swallow. Time for you to replace a new battery or your may damage your trackpad and hardware. You may search "Key Power apple battery" on amazon and order one. I recommend their product because it is very reliable.
Swollen battery and cracking laptop.