This is a really good question. If your battery is dead your key won't open the trunk (or boot, in your case) to get at the battery to replace it. The Mercedes Benz key not only has buttons but it has a metal key in the base. There is a hole in it for the key ring, if you use a key ring, and a slide that allows the metal key to come out.
This key is supposed to be able to open the boot (or trunk, in my case.) I say 'supposed to' because not a few folks report difficulty with using this key.
Another option is to purchase the proper battery for your car and hook it up to your electrical system. You can do this under the hood (bonnet) at a special red (positive) terminal that is available to you. Attach the negative terminal of the battery to the frame and the positive terminal to this special access point.
Your key should then open the boot as normal.
In a 1998 Mercedes-Benz E300, the battery is located in the trunk of the vehicle, specifically on the right side. To access it, you'll need to lift the trunk floor cover. This placement helps with weight distribution and keeps the battery protected from the elements.
The battery is located in the trunk.
The battery is in the boot
In the 1994 Mercedes-Benz E320, the battery is located in the trunk of the vehicle, specifically on the right side. To access it, you may need to remove a cover or panel. This placement helps with weight distribution and maintenance of the vehicle's performance.
In the trunk on the right.
in the boot
Most Mercedes Benz Techs will suggest replacing your battery every 7 years.
The battery of a Mercedes Benz CL600 as of 2002 is located in the rear trunk on the passenger side.
You are driving a Mercedes Benz. Learn these words; "I have people for that."
In a Mercedes-Benz GL450, the auxiliary battery is typically located in the rear compartment, specifically beneath the cargo floor. You may need to lift up the floor cover to access it. Always consult the vehicle's owner's manual for precise location details and safety instructions before attempting to service the battery.
under the right front seat
trunk