ric3pluto

Good morning fellows,

I am in quite the pickle with my lovely and definitely reliable Mercedes-Benz/Mercedes-AMG GmbH trunk.
Recently, my battery had gone dead and that alone was its own problem to solve (now fixed), but ever since then I have been having troubles with my trunk.

How to achieve my predicament:
Step 1 - have a dead battery
Step 2 - open the trunk with your mechanical key
Step 3 - close the trunk by pushing it down
Step 4 - ???
Step 5 - charge the battery and get the car running again
Step 6 - realize you can no longer open the trunk with the interior trunk release button, or either key fob button, or either mechanical key

I was able to open the trunk prior to my battery dying with the interior trunk release, key fobs, and mechanical keys, but now none of them work. When I insert the mechanical key, it goes in most of the way, maybe 80-90% of the way, but not fully, so I cannot turn the key at all. Both of the mechanical keys are NOT bent.
I've tried WD-40, manually (softly) trying to dislodge anything that may be in the lock, and many times using the automatic trunk release. There is a slight bit of play upwards and downwards when pulling the trunk. There is no access point from the outside of the trunk, with the license plate removed, there are no holes or screws.
My main thought is the trunk may have been closed incorrectly or the latch was closed incorrected when the battery was dead, thus leaving me with a locked trunk. I don't remember if I removed the key while the trunk was open or after I closed it. I also couldn't find anything online in my same situation, specifically with the mechanical key going mostly in.
Anyone have any ideas? I need to access my trunk for very important "Business" reasons.
Thanks all <3

Mark out West

If the doors open correctly via the exterior door handle and via the remote, then perhaps the trunk key is stuck in the "valet" position? Did you turn it back to the original position before you removed the key?

ric3pluto

Both doors open correctly via key fob and the driver side door opens correctly via mechanical key. The trunk lock is locked in the vertical position, not the horizontal valet position, but I can't fully insert the key, which also means I can't turn the lock at all. I'm thinking something about the locking mechanism is jammed, or the trunk was closed improperly. Pushing down or pulling up on the trunk doesn't change anything, including doing both of those actions while attempting to insert the key.
At this point, with the lack of online resources, would consulting a locksmith be a good idea? Or is this the case of a fault mechanism that would need to be replaced?

ric3pluto

I don't recall how I removed the key, but the lock is in the vertical position. I feel it may have closed incorrectly due to the key only going in maybe 90% of the way. The left side of the trunk panel is flush with the side panel, but the right side is 1 or 2 millimeters above from flush, which is also the side that has play. Any other ideas? At this point I may need to remove the rear seats.

Mark out West

On my car, removing the key in the vertical position triggers "valet" mode. Rotate it counterclockwise 90 degrees, remove the key, and see what happens.

The owner's manual shows the vertical position is being unlocked, and a 90 degree turn to the right as "valet". Beats me why mine is horizontal.

ric3pluto

Unfortunately, with the key not being fully inserted, there is no rotation movement of the lock, the key can jiggle slightly, but the actual lock doesn't move at all.
It's possible to get a lockpick all the way in the mechanism, just not the key itself. I would assume that means there's an issue with the key, but I used a brand new one and it still doesn't insert.
Any idea of whether it's possible that the latch closed before the lock closed, if that makes any sense? Could also be vice verse, the lock closed but the latch didn't, hence why none of the buttons make any noise, and it could lead to excessive tension on the lock preventing the key from inserting.
Thanks.