My battery had swelled and was very stuck. First I carefully stuck a narrow pry tool between the battery and the housing which allowed the ribbon cable to be slid out without damaging it. Then I added some 99% isopropyl alcohol down the sides of the battery to loosen any adhesive. I was first able to wedge a plastic spudger down the side of the battery and wiggle it back and forth, then I used inertia to slowly move the battery out of the housing by banging the whole speaker on a solid piece of wood until I could grab the battery and remove it. This way you don't have to pry at the battery and risk puncturing it.