I couldn't find any DIY, tips or tricks that solved the problem I had on my 01 E39 M5. Front passenger door was stuck double locked aka dead locked and could not be opened from either the inside or outside.
The tricks I tried but failed to solve the problem included taking the battery terminals off for 1 hour and connect them with each other to drain all power, supposedly resetting all the modules; hitting the open/close locks button 100 times or slamming on the inside/outside of the door. Im sorry I didn't take too much pictures during the process but will try to write it down as good as possible.
I recommend buying a new door lock actuator before starting the fix, so after removing the airbag the airbag light will not illuminate.
Tools that I used:
Torx (for inside door handle)
short/shallow 10mm socket + ratchet
10mm spanner
long flat head screwdriver
Lower window.
Take the black glossy piece of trim from the top/inside of the door, just pull up.
Working from outside, push the door card inwards so you have a workable gap, you will be able to lift it over the (chrome) rod.
With a screwdriver, pop out the airbag cover. It will break some foam but it is easy to glue this bag together with no visible damage.
Disconnect airbag and remove the bolts holding the airbag in place using the ratchet for the top 2 and the spanner for the bottom one.
Pull airbag out through the gap on top.
Disconnect door lock actuator.

Using a long flat head screwdriver, pry below the white plastic on the actuator where the physical lock is located and it will pop open.

Now you will be able to remove the door card and replace the FUBAR actuator.

Images are clickable for higher resolution. I did not disconnect the battery but I strongly recommend doing so, just to be safe while working with explosives.
The tricks I tried but failed to solve the problem included taking the battery terminals off for 1 hour and connect them with each other to drain all power, supposedly resetting all the modules; hitting the open/close locks button 100 times or slamming on the inside/outside of the door. Im sorry I didn't take too much pictures during the process but will try to write it down as good as possible.
I recommend buying a new door lock actuator before starting the fix, so after removing the airbag the airbag light will not illuminate.
Tools that I used:
Torx (for inside door handle)
short/shallow 10mm socket + ratchet
10mm spanner
long flat head screwdriver
Lower window.
Take the black glossy piece of trim from the top/inside of the door, just pull up.
Working from outside, push the door card inwards so you have a workable gap, you will be able to lift it over the (chrome) rod.
With a screwdriver, pop out the airbag cover. It will break some foam but it is easy to glue this bag together with no visible damage.
Disconnect airbag and remove the bolts holding the airbag in place using the ratchet for the top 2 and the spanner for the bottom one.
Pull airbag out through the gap on top.
Disconnect door lock actuator.

Using a long flat head screwdriver, pry below the white plastic on the actuator where the physical lock is located and it will pop open.

Now you will be able to remove the door card and replace the FUBAR actuator.

Images are clickable for higher resolution. I did not disconnect the battery but I strongly recommend doing so, just to be safe while working with explosives.