Nano Door Contact
Note: You will need a small flathead screwdriver.
Insert the screwdriver into one of the notches on the corners of the device and pry off the cover.
Locate the battery.
Gently slide out the battery.
Note the battery terminals (+, -).
Place a new battery in the device (CR1632).
Replace the cover on the device, ensuring the corners match up.
Press in until you hear a click.