In order to Reset the Fibaro door/window Sensor, follow the below procedure:
Remove the front cover of the Fibaro door/window sensor.
Disengage the battery from the slot.
Press and hold the TMP button while simultaneously inserting the battery.
Release the TMP button.
The LED will blink three times acknowledging that the reset program is launched.
Wait for 30s meanwhile if the LED indicator blinks six times, the sensor is reset.