1. Pull out the auxiliary key.
2. Replace the cap using a flathead screwdriver, then rotate and remove the cap.
3. Insert a flathead screwdriver into the crack and press the battery out.
4. Insert the new battery (CR2025) with the positive pole (+) facing the (+) mark on the cap.
Battery specification
5. Rotate and close the cap.
6. Reinsert the auxiliary key.