If the screen of your phone is off, it means that it is not getting power. Check the power supply is correctly connected to the power outlet, and it is connected to the phone. If everything look correct, the power supply may have failed. You can order more from us directly or purchase your own by ensuring it's a 5v 1000mah power supply. 

If you are running over PoE (Power over ethernet), please ensure the cable is corectly connected to the phone and to the switch. Also the switch must be on.