Display shows F14; opener beeps; battery backup (if equipped) does not function.

Safety first: Disconnect AC power before servicing the battery. Batteries can leak corrosive electrolyte.

• 1. Locate battery compartment: On Linear models with backup, open the battery cover on the head unit.
• 2. Inspect battery: Check for swelling, leakage, or corrosion on the terminals. If present, the battery must be replaced.
• 3. Check connections: Ensure the battery harness is firmly plugged into both the battery and the control board. Clean any corrosion with a baking soda and water solution, then dry thoroughly.
• 4. Test battery voltage: Use a multimeter to measure battery voltage. If it is significantly below the rated voltage (e.g., under 11 V for a 12 V battery), replace it.
• 5. Replace battery: Install a new, compatible Linear backup battery. Observe correct polarity.
• 6. Verify charging: Restore AC power and confirm that the F14 code clears after a short period. If it does not, the charger circuit on the control board may be defective and the board should be replaced.