There are 11 stretch-release adhesives that secure the battery to the frame. Each adhesive strip has a black pull tab:

Six on the inside edge of the left battery

Five on the inside edge of the right battery

The remainder of the adhesive is located along the bottom edge of the battery.

Use your fingernail or tweezers to peel each pull tab from the edge of the battery without removing them.

Be careful not to deform or puncture the battery—especially if you're using tweezers.