Insert a flexible plastic tool on the left edge of the battery. We use an opening pick here, but a playing card is a safer (albeit slower) option.

Gently pry up the battery with constant steady force.

Try to slowly release the battery's adhesive without deforming the battery. If the battery begins to bend out of shape, pry slower or apply more heat/isopropyl alcohol. Several rounds of heating or alcohol may be necessary.

Slowly work your tool underneath the battery and continue prying until it is completely released from its adhesive.