I had the issue with the 3rd brake light, license plate lights messages and the trunk wasn't opening or closing. I repaired the cut brown wire and everything is working except the trunk release.

When I have the blade key in and turned, the trunk opens and closes normally either manually or with the door buttons. With the trunk lid open (and the blade key still in) you can hear the trunk release work when pulling on the trunk release switch on the door.

Electrically, everything seems to work. Until I remove the blade key and the release stops working again. It closes and the red trunk close button is lit up. I can't even open the trunk manually unless the key is inserted.

Any ideas? (2009 E550)

 

Update:

Finally figured out that I was turning the key too far back and activating the Valet lock. Turning the key back halfway and removing fixed the issue.

Relieved and embarrassed that I didn't figure it out quicker.

 

Glad you figured it out we won't laugh too hard we have all been there