My battery was so firmly glued in, it took a long time to slowly pry it loose. Patience is the key to this process. I could see easily damaging the circuit board by using too much force. The plastic tab did not help at all.
The ribbon cable attaching the new battery to the battery connector clip is longer than the original. I clicked the clip into the socket first and then was very careful to fold the excess while putting the battery back in so the ribbon cable didn't kink. One kink in this could sever the battery leads.