Is activated because something got caught between the rotating tweezers or because you pressed the appliance too hard onto your skin. When the overload protection has been activated, the speed setting indications flash red. Turn the tweezers with your thumb until you can easily remove the item that is blocking the rotating tweezers. Then switch the appliance on again. Do not press the appliance down too hard onto your skin. Your device cannot be used without being connected to the mains.
If this did not help you, please contact your local Philips dealer.