Battery expanded against track pad which stopped clicking, also the MAC lid would not close completely.
Repair is straight forward, just take your time and you'll be fine.
The battery is a series for pouches. Lift up slightly one at a time, do not try to pry it out. If you hold on to it with slight pulling force, it'll give slowly. Forcing it will probably damage the MAC or battery making a mess. If you do it in a warm to hot room it'll peal easier, stay away from heat gun or hair dryer.