Had the same problem as many posters on here. I hadn't appreciated just how many were suffering what is a pretty serious design fault. Surprised Volvo continued to use these mechanisms year in year out knowing full well this is a safety issue.
I followed this link which proved very useful.
https://www.youtube.com/watch?v=-TjMw6ORydA
The removal of the panels and the door card was relatively straightforward, except the torx 25 screw in the door which is very restricted by the middle post between the front and rear doors.
I used a torx tool with a 90 degree angle and aligned it vertical to vertical if that makes sense, as this seemed the only way to remove the tool.
However the screw is relatively flexible so you can get a straight torx in at a bit of an angle.
Disconnecting the speaker and windscreen wiper connectors is very easy - the blue one at the top and the grey at the bottom.
Disconnecting the door cable is more difficult and care is needed not to break the plastic clips.
The really difficult bit is poking around the hole to try and reset the door latch - took me almost 45 minutes to get it to trip open and even then I wasn't sure it had worked.
Once released though it is easy to reassemble everything with the door fully open. Applied loads of WD40 to the lock and through the hole at the latch.
Larry