1. Which battery it takes
Many remotes use a CR2032 coin cell. Older and larger ones use an A23 or A27, which are 12-volt stick batteries about the size of a thick pencil. Check the old battery for the code.
2. Open the case carefully
Remotes are usually held together with screws or a clip. Note which way round the battery sits before you take it out.
3. Put the new one in the same way
Match the + and – marks on the battery to the contacts. A battery in backwards often gives you a remote that only works from close to the door.
4. Pair it again
Most remotes need re-linking after a battery change. Press and hold the main button until the light stops blinking, or press the button a few times until the door reacts. Your manual has the exact sequence.
5. The wall button and the motor have batteries too
If the remote works but the wall button doesn’t, the receiver or the motor have their own battery pack. That’s usually a sealed pack behind the panel that a technician replaces.