To Turn on the sensor, push the button on the rear once.  The LED on the front will momentarily flash blue, indicating the unit is on.
To Turn OFF the Sensor, press the button twice in 2 seconds.  The LED on the front will momentarily flash green and then red, and the sensor is OFF.
To Reset, hold the button on the back for ~ 4 seconds, and the LED on the front will blink, and the unit will restart in a few seconds.