If they won't put voltage to the car via the method described above then you should do it yourself. It works just fine and saves the cost of drilling out the old lock.

 

Thanks for that. I connected a battery charger to the hot wire and tried the trunk release switch. It made a noise but didn't properly open trunk - then tried key again which I previouskly hadn't been able to move and this time it turned and I was able to open the trunk.

 

Thanks so much for this tip. It was a big help. I called the Mercedes Roadside Assistance, and even the tech couldn't open the trunk. Then I showed him you picture. We gave it a shot and it worked. This is the way to go; much easier than messing with the trunk. Thanks again.

 

just get one of these

http://www.amazon.com/gp/product/B00...=ATVPDKIKX0DER

dont use it to start the car...just plug it into your cig lighter when your battery is dead, and it will give enough juice to pop the trunk

 

As others have noted the key will work (assuming it is the right one for the car). It just takes time and patience. Some have mentioned using WD-40 so I tried that and had some limited success in getting the key in. I then used a product call Freeze-Off and after messing with it for 1/2 hour or so it worked. I sprayed inside the lock and on the metal key and just played with it back and forth. Not sure if its the same on all cars but for mine I inserted the key in the opposite direction than the pos ition used to open the driver side door. On the door the lip you hold onto faces down when you are inserting it it looks like
L___________ from the side, for the trunk the L is upside down. Hard to explain clearly but it kind of looks like the trunk takes it upside down. After using the lubricant I inserted the key, back and forth, jiggling, pushing, etc. I couldn't believe it made it all the way in. Remember you need to get it so the key is all the way in before turning and pushing. Once I got it in I used a pair of pliers to turn the key slighting left, slighting right, back and forth, being very careful so as to not break off the key. Didn't think I was getting anywhere but all of a sudden it turned. To open is like a 30-45 turn to the left and then you push the button and trunk opens. I have been having a bunch of electrical issues that may or may not be related but after I got the trunk open using the key I can now open the trunk using the cabin trunk switch and the key fob neither of which worked before.