You would obviously need the key for this but it would release the garage door without resorting to prying it with a hanger or another similar hack.
Pry garage door open.
These things can leave you at the mercy of a lo.
If the power comes back on the opener might attempt to open the door while it is disengaged which can make it harder to reconnect.
If you do not have an entrance door to your garage either to the interior of your house or the exterior there should be a key based garage door release on the outside of your garage.
On either side of the garage door place two 6 foot ladders.
Unplug the automatic door opener.
Unplugging the garage door opener before you try to manually open or reconnect your garage door will keep you safe.
In order to do it properly and safely you can follow these steps to open your garage door with a broken spring.
The trolley moves along the chain drive the long track attached to the ceiling when the garage door is opening or closing attached via a metal bar to the inside top of the garage door.
Get two crowbars or pry.
These openers use a threaded rod to push and pull a trolley that lifts and lowers your garage door with ease.
For a garage door opener that is quieter than your typical chain drive model consider the convenience of a screw drive garage door opener.
These ladders will help keep the garage door open when you manage to prop the door open all the way.