When you aim at the unit with the remote and click the On/Off switch you should see the power button (one all the way to the left that is Red) blink. If that's not the case then the remote is not working or the main unit is not reacting to it. Betting on the remote. You might want to fiddle with the remote's battery (assuming there's nothing in the way of the battery properly connecting to its contact points - some bit of plastic or such remaining inside the battery housing). If you have a programmable remote, you might want to test to see whether it can pick up on the Darblet's remote (that would confirm whether it's a problem with the remote, versus the main unit's sensor).