If you have a spare garage door opener does that mean there is no other way of opening the garage? What do you do if the power goes out but you need to get the car out of the garage? What can be done ...
Most garage door openers do have a manual override for just such an event like power going out. If you look at the central bar that runs from the gear box to the top of the door you should see a rope cord hanging down. Pulling this will disengage the gear box from the chain that opens and closes the door.
Pull that cord and you can then open the garage door by hand. When the power comes back on just climb up a ladder and snap the connector at the end of the cord back on to the chain. I spent more time getting the ladder out than I did reconnecting the chain last winter when our power went out.
I hope this helps. If you need more help just let me know.