Disconnect the plug from the thermal relay.
Short-circuit the two contacts of the plug with a piece of insulated wire. If the fan starts working, then the thermal relay is faulty, which in this case interrupts the current circuit.
To continue driving, put a jumper between the contacts. In this case, the radiator fan will work constantly.
To prevent loose wires from causing short circuits, insulate them with electrical tape or scotch tape.
If bypassing the thermal relay does not help, apply battery voltage directly to the motor contacts.
Original source of information: MitsubishiMan
If the motor does not rotate, it is faulty. In this case, the electric motor needs to be replaced.
CAUTION: If there is a jumper, it must be disconnected after the end of the movement, otherwise the fan motor will run until the battery is discharged.