Hi, I was having some problems with my car after getting it back after a B-Service, I don't know if it's a coincidence.
My windows would not roll all the way up when I exit or enter the vehicle, I had to open and close the door a second time for the windows to roll up.
There were also issues with the door mirrors only opening halfway when entering the car as well as the seat not moving forward or adjusting when the door is open, and the radio had no sound from time to time.

Today I tried disconnecting the battery for 30 minutes, hoping that it would reset whatever was wrong, but now I can no longer get access to the boot/trunk.
I turn the key and the boot/trunk unlocks, but not fully. It opens about 1/4 of an inch but is still caught on the latch/locking mechanism.
I have done a Google search and found that some Mercedes boot locks have two stages, if this is correct, then my car may only be unlocking the first stage and not the second.

Can anyone offer some advice on how to gain access to the boot?

 

I found a solution, all I needed to do was unscrew the 3 torx bits next to the locking mechanism and push the locking mechanism into the trunk/boot and it springs open.
Here's a Youtube video, you will need to remove the licence plate and the carrier panel, there are other videos online that show you how to do this: