Impala actuators

I'm in the midst of replacing the driver's side
actuator for the second time and when plugging in
the new one it began to turn. Now, I probably
should have disconnected the battery but I didn't
even so the actuator shouldn't be running when the
car is off right?  So might it be a faulty contact,
terminal, or....? I don't know much about cars,
electrical stuff, or anything really but I know
eventually plastic teeth on a gear will break if it's
continues to try turning a post that is not moving.
Thank you all for sharing!