When I press the button, the opener is on (I hear the sound) and the light is on too, but the door does not open (the chains do not move). The light went off after 3 minutes as usual. What can be the problem?

The brand name of the opener is Challenger, model CH-1000.

Steven

The shear pin on the shaft that moves the gear may be gone (Broken) or shaft itself broke near motor.