Is the printer off?
Press the I on the power switch to turn the printer on.

Is the power cord loose or disconnected?
Turn the printer off and connect the power cord properly. Turn the printer on again.

Is the printer connected to a correctly rated outlet/socket?
Connect the printer to an AC power outlet/socket that you know works. Do not connect any other equipment to the outlet/socket. Do not connect the printer to an auxiliary power outlet on the back of a computer.

Is the printer defective?
Turn the printer off immediately, disconnect the power cord from the outlet/socket, and contact your dealer or Brother Customer Service.