Opener shows E10 or ten flashes; battery backup (if fitted) does not operate the door during mains failure; low battery warning may sound.

Safety first: Disconnect mains power before working on the battery. Observe polarity when connecting battery terminals.

• Step 1 – Check battery age: Locate the B&D backup battery pack. If it is more than 3–5 years old, it is likely due for replacement.
• Step 2 – Inspect connections: Ensure the battery harness plug is fully seated in the control board and that the battery terminals are clean and tight.
• Step 3 – Measure battery voltage: Using a multimeter, measure the battery voltage (typically 12 V DC for many packs). If it is significantly below rated voltage, replace the battery with the exact B&D‑specified type.
• Step 4 – Test charger: After installing a new battery, restore mains power and allow several hours for charging. If E10 remains and the battery does not charge, the charger circuit on the control board is likely faulty.
• Step 5 – Replace charger/board: If the battery is good but not charging, replace the control board or dedicated charger module as per B&D documentation.