3. Remove the backup battery by turning it slightly counterclockwise, and pulling it out.
Backup
Battery
4. At the same angle, place the new battery (positive side facing away from the main battery) at the edge of the track. As you push it in, it will straighten itself.
5. Replace the main battery.
6. Slide the compartment door shut. You will have to press the main battery in slightly so the door fits over it. When the door shuts, you hear it click into place.
Using Batteries