When removing the battery, check the label of a battery polarity connection, otherwise put labels.
1. Using a thin blade screwdriver, remove the head (1) with the key (2).
2. Press the tabs on both sides of the head and remove the head cover.
3. Use a screwdriver to press the lock (2) and remove the top of the battery (1).
4. Remove the contact plate (1) by turning it so that the two cut edges located opposite the clamps and using a blade screwdriver, remove it from the head.
5. Remove the bottom of the battery.
6. Install the battery in the bottom of the head so that the positive pole of the battery facing down. On the positive pole of the battery has a plus sign (+).
7. Replace the battery contact plate and the positive pole of the upper battery down until it snaps into place.
8. Replace the head cover until it snaps into place.