A flashing red On light indicates the unit is powered and ready, but no speed is selected. This is normal.
Press a speed button (1-7) after the On light flashes. Both the On light and the speed light will glow, and the motor will run.
If you press On and a speed but nothing happens, the jar may not be fully seated. Ensure it's positioned so the jar markings face you and the handle is to the side.