There should be two solenoids. The top one controls the dowm movement and the bottom one controls the up movement. If the unit is not working at all always search for the fuses that are inline with the power source to both solenoids. They may be more the two so search good.
Connect a 12 volt battery across the two small terminals. The ohm meter should read 0-ohms indicating continuity and an audible click should be heard. The click will verify the plunger is mak9ng contact with the inside terminal to close the circuit
If the ohm meter shows a resistance in the solenoid and you don't hear the click the solenoid is bad
If both solenoids check ok the check all conections and the charge on the battery.