Note: The glass break is generally mounted on the ceiling.
Pop off the cover, pulling from the side with the light and microphone.
Remove the cover and locate the batteries.
Gently remove the batteries.
Note that the two battery terminals have the positive sides facing each other.
Place new batteries in the device (CR123A).
You will see a light blink to signal that the device is operational.
Replace the cover on the device.
Press in until you hear a click.