Changing your Mercedes-Benz key battery is a simple process which should only take a few minute to complete. Below is a simple step-by-step guid to help you through the process. Please be advised that most Mercedes-Benz keys require a CR2024 battery.
1) Located at the top of the key fob, push the slider to one side and pull to release the key blade.
2) Push the key blade into the gap adjacent to that vacated by the slider. This will release the back of the key fob, allowing access to the battery.
3) From here you will be able to replace and test the new battery before reassembling the key.