To reset your door / window sensor, just follow the simple steps below.
1. Take the cover off the door / window sensor
2. Remove the battery
3. Use a small object (like a pencil eraser, or the end of a cotton swab) and push down on the reset button (small silver button above the plus sign)
4. While pushing down on the reset button, re-insert the battery (the light will be orange)
5. Put the cover back on
a. The blue light should blink 3 times to indicate the sensor is ready to pair.
6. Follow the on-screen, step-by-step instructions to pair, name, and test the sensor