Step 1: Gather Your Materials
 

Before beginning the battery replacement process, ensure you have the necessary materials:

• A new CR2032 battery.
• A small, flathead screwdriver or a similar tool.

 
Step 2: Remove the Emergency Key
 

• Locate the small, rectangular button on the side of the key fob.
• Press this button to release the emergency key from the key fob.
• Pull the emergency key out of the key fob.

 
Step 3: Open the Key Fob
 

• With the emergency key removed, you will see a small notch or gap where the key was inserted.
• Insert the flathead screwdriver or similar tool into this gap.
• Gently twist the tool to pry open the back cover of the key fob, exposing the battery compartment.

 
Step 4: Remove the Old Battery
 

• Note the position of the old battery to ensure the new one is inserted in the correct orientation. The positive side, typically marked with a '+' symbol, should be facing up.
• Use the flathead screwdriver to gently pry out the old battery from the compartment.

 
Step 5: Insert the New Battery
 

• Take the new CR2032 battery and align it with the battery compartment, ensuring the positive side is facing up.
• Press the battery firmly but gently into place to ensure it is seated correctly.

 
Step 6: Reassemble the Key Fob
 

• Align the back cover of the key fob with the front section.
• Press both halves of the key fob together until you hear a click, signifying that it is securely closed.

 
Step 7: Replace the Emergency Key
 

• Insert the emergency key back into the slot on the side of the key fob.
• Press until it clicks into place.

 
Step 8: Test the Key Fob
 

• With the new battery properly installed, test the key fob’s functions such as lock, unlock, and trunk release to ensure it's working correctly.

If the key fob does not work, double-check the battery's orientation and make sure the fob was assembled correctly. If issues persist, consider consulting a professional or a local Mercedes-Benz dealership for assistance.