This is probably what is going on. The most likely failure mode for a vacuum can would seem to be a leak where the vacuum won’t operate it. Can you pull the vacuum actuator rod off the door to check to see if the door and the actuator both move freely?
I could also be a vacuum switch malfunction. Take the hoses off the actuator & see if that lets you move it, or easier yet, push the buttons a few times with the engine off to drain any captured vacuum & see if the door moves then.
