AG1 and AG9.

1. Place the battery with the printed side facing up, confirm the installation position of the button battery, then pick up the button battery, and place the button battery with the printed side facing up.

2. Put the battery into the card slot, with the side with the battery ring facing down, and then place the button battery in the battery card slot.

3. Press the battery down with a little force. When you hear a click, it means that the button battery has been installed.