DIAGNOSIS The auger motor is seized or jammed solid. The clicking is the internal thermal protector tripping because the motor can't move.
FIX Unplug the grill. Empty the hopper. Access the auger system. First, try to manually turn the auger shaft. Find the cleanout cap on the back of the grill, remove it, and use a socket on the exposed auger shaft bolt. Turn clockwise. If it won't budge, you have a severe jam. You must disconnect the auger from the motor (usually a shear pin or set screw) and clear the tube.
IF THAT DIDN'T WORK If the auger turns freely by hand but the motor still clicks, the motor is burnt out. You need a new auger motor assembly. Match the part number from your old unit.
HEADS UP Never force the auger by running the motor. You will burn it out. Always clear jams manually first.