Establish whether the problem is only a loss of power
Note whether other equipment in the garage also lost power and whether the door was operating normally before the outage. Do not open electrical covers or attempt wiring repairs. A power interruption does not explain away a hanging cable, a damaged panel, or a loud bang heard earlier.
If the door was already malfunctioning, tell the contractor both facts: the previous symptom and the later outage. Keeping that sequence clear can prevent a power problem from being confused with a separate mechanical fault.
Use the exact manual, not a universal release sequence
Emergency-release arrangements and reconnection instructions are model-specific. Locate saved paperwork or an accessible equipment label. Do not climb beneath an open door to obtain a number, and do not pull the release on an open or unbalanced door.
If you cannot identify the equipment or the instructions do not match what is installed, ask for professional guidance. Do not force a heavy door or use a vehicle to lift it. Choose another entrance when one is available.
Sources: CPSC opener safety alert
Battery backup is an equipment feature to verify
Some openers include battery backup, but its presence and working condition must be established for your model. A phone app alone does not prove the opener can operate without mains power. Ask about battery condition, replacement instructions, and the manufacturer's stated operating limitations.
If outage access is a priority for a replacement opener, include it in the installation brief. Confirm the proposed model's backup capability rather than assuming an optional accessory is part of the price.
After power returns
Before using the door, check that people and belongings are clear and follow the manufacturer's reconnection instructions if manual operation was used. Stop if movement is abnormal. Do not repeatedly reset an opener that continues to show a fault.
When calling for help, explain what was done during the outage, the door's present position, and any messages now displayed. That history is more useful than describing the opener as simply dead or broken.