Take lots of time to very gently pry battery out. Carefully, so as not to rupture the battery skin, insert a steel ruler 1mm thick 3cm wide under the short side. Push gently and wiggle left and right. When it doesn't slide further without force, leave it somewhere safe (fire) at body temperature (soften glue), with the ruler in place. Do not overheat beyond body temp. Wait 15 minutes and repeat pushing and waiting. The battery will eventually let go with virtually no bending at all. Certainly no deformation as shown in the pic here.