THANKS A MILLION BRIAN!
Few days ago the door of my 2004 X5 3.0D stayed unlocked after opening it.
Meaning I could close it but it would not latch.
After trying to close it a few times it did close but would not open anymore....
Had to enter the car via the passenger door.
When pulling on the outside door handle I did not feel any resistance anymore and the inside door handle didn't do anything either.
The electric lock did work as usual.
A search on youtube revealed some vids on how to replace the door lock actuator and how to repair a door handle.
The BMW dealer told me it could be a tough job to replace the lock mechanism with the door being closed...
Managed to get the panel partly loose without damaging it but could not do anything further apart from trying to push/pull every metal item I could feel.
Decided to order a new door lock in the mean time (51218402537).

In the evening I started searching again for a fix and came across this topic.
Made a stiff rod as per Brian's specs and within a minute the door was open!
removed the inside panel completely and could open/close/lock/open the door as usual.
Will remove the lock tomorrow and apply a good coat of grease on the moving joints.
Thanks again Brian!