Battery Tutorial: Door Window Sensor (DW10)
"You will need two CR2032 batteries to change the batteries in your sensor.
Before changing the batteries, make sure that your system is disarmed and note that you may here some beeping from the panel when you open the sensor.
Go to your door sensor and press the tab on the side to open the sensor.
Remove the old batteries and replace it with the new CR2032 batteries.
Replace the sensor cover and make sure that it snaps shut with no gaps.
Remember to safely dispose of the old batteries.
For more information and tutorials, please visit support.vivint.com"