Display shows code 18, battery backup LED flashing (on models with backup), opener may not run on battery.

Safety first: Disconnect mains power before working on the battery. Batteries can leak corrosive electrolyte.

• Locate battery pack: On Merlin models with battery backup, the battery is usually in a side or rear compartment. Open the cover and inspect the battery.
• Check connections: Ensure the battery leads are firmly attached to the terminals and not corroded. Clean light corrosion with a baking soda solution and dry thoroughly.
• Check age: Most sealed lead‑acid batteries last 3–5 years. If older, replace with a Merlin‑approved replacement battery of the same voltage and capacity.
• Test operation: With mains unplugged, try operating the door. If it fails even with a new battery, the charger or battery management circuit on the PCB may be faulty.
• Replace battery module: Some models use a plug‑in battery backup module; replace the entire module if available.