Micro Door Sensor
Note: You will need a small flathead screwdriver.
Find the notches on the top corners of the device.
Using the screwdriver, pry off the cover of the device. The easiest way is to insert the top of the screwdriver in the notch and twist.
Remove the cover.
The device has an inner cover, remove this by popping it off with the screwdriver as well.
Carefully remove the circuit board.
Gently remove the battery.
Note the battery terminals (+, -).
Place a new battery in the device (CR2032).
Place the circuit board in the device, and replace the inner cover.
Place the cover back on the device.