To open a garage door with the power out, pull the red emergency release while the door is closed, then lift it by hand. A balanced door feels light. If it feels like a brick, stop.
The opener needs power. The door does not. A working door is balanced by its spring, so one adult can usually lift it by hand once the opener lets go. The trick is letting go the right way, and knowing when the door is telling you to stop.
If the opener beeps or still moves on its own
Some openers carry a backup battery. You may hear a beep every so often, or the door may run slowly for a few cycles. Use it to get the car out, then leave the door closed until the power is back. Those batteries are meant for a few trips, not a whole day of open and shut. If the beep keeps going after the power returns, the battery is likely old and wants a swap.
California has required a battery backup on residential openers sold or installed there since July 1, 2019, under Senate Bill 969. Plenty of homes elsewhere have one too. Many older openers do not.
If the opener is dead and the door is closed
This is the safe case. Look for the red handle hanging from the rail near the door. Pull it down and back toward the motor. You may hear a click as the trolley lets go of the carriage on the door arm. Now grab a handle or the bottom section and lift.
A healthy door rises smooth and feels light, maybe twenty or thirty pounds of effort. It should stay put about halfway when you let go. Lift it all the way, keep clear of the track and the gap between sections, and prop nothing under it. Back the car out, then pull it down by hand the same way.
If the door is open when the power dies
Be careful here. Pulling the release on an open door is how doors slam. If the spring is weak or broken, the door can drop the moment the opener lets go. If you have to close it, get a second adult, have both of you hold the bottom section, then pull the cord and lower it slow. If you cannot hold it, leave it open and lock the house door instead.
If the door feels like a brick
Stop. A door that will not lift or wants to crash down is not balanced. That usually means a broken torsion spring or a frayed or slipped cable. The opener was hiding the problem by doing the lifting for you. Do not use a pry bar. Do not wedge a board under it. Take a ride or call a shop.
If you are outside and the door is locked
Some homes have a small key lock on the outside of the door that trips the release from outside. If yours has one, it works only with the key that came with it. If not, there is no clever hack worth damaging the door over. Get in through the house.
When the power comes back
Plug things back in if you unplugged them. Run the opener once with the trolley still free so it travels the rail. On most units the trolley catches the carriage on its own, or after you pull the cord toward the door. If it will not grab, see when the red cord will not reconnect.
Then test both remotes. Some boards forget them after a surge, and you are back at a remote that does nothing. A few boards also fire an open on reboot, like a door that opens by itself. Watch the first close with the little lights by the floor. If a light blinks, wipe or nudge the eyes.
What not to do
Do not run an extension cord from a car inverter to the opener unless the manual says it is fine. Do not leave the door open overnight because you cannot close it alone. Do not try to tighten anything on the spring or cable while you have the door free.
I am not a contractor. This is what comes up most when the power goes out and people wonder if the door broke too. Most of the time it did not. A shop can add a battery backup or replace an opener that cannot take one.
DASMA's garage door safety tips cover balance checks and keeping hands clear of sections. The U.S. CPSC garage door operator page covers federal rules for automatic openers.
If the door felt heavy or the opener never woke up after the power came back, get a quote.