When you get tired of guessing, check the motor control board down below. If it is bad, the machine will fill for a minute or so, then the unit will shut down completely, no lights nothing. Visible signs on the board include a blown fuse and/or dark scorch marks around resistors. I found an identical issue yesterday.
The quick way to tell if the motor is out is to set the timer on a spin cycle, open the door and hold the door switch down, then press start. You should see the tumbler go back and forth as though it were washing. If it does not move within 5 seconds after pressing start, the motor control is bad.