Replacing the battery for the remote control keyReplacing the battery for the remote control 
key  - Remote control keys - Doors and windows - Controls - Audi S5 Owner's Manual - Audi S5

Each remote control key contains a round-cell battery, located in the battery carrier.

Fig. 29 Remote control key: Removing the emergency key
Fig. 29 Remote control key: Removing the emergency key

Fig. 30 Remote control key: Removing the battery carrier
Fig. 30 Remote control key: Removing the battery carrier

Ц Press the release button A.
Ц Pull the emergency key B out of the remote control key.
Ц Press the release catch A on the battery carrier and at the same time pull the battery carrier out of the remote control key in the direction of the arrow.
Ц Insert the new CR 2032 battery with the У+Ф symbol facing downwards.
Ц Slide the battery carrier carefully into the remote control key.
Ц Insert the emergency key.

For the sake of the environment
Used batteries must be disposed of appropriately and must not be discarded with ordinary household waste.

Note
The new battery must be of the same type as the original one (CR 2032).