Thanks.
Heres my situation.

Of course, as most of W140's, my close door assist works for at least two times to like days(when its cold).
But that worked until two days ago and the close assist still works at the doors.
I checked the fuse #3 at its fine.
When I press the button that opens the trunk (after previously manually pressing the lock inside) you can hear the sound things moving(so I guess the pump is ok) where the latch is, but the latch doesn't come out.

I hope this helps.