Finally got some time to get to this. Got door skin off, basically had to pull off the pillar plastic to give a bit of room to undo the screws by the pillar. Then undid the 2 at the bottom, but no access to the ones on the swinging side, so pulled... only broke one, so door skin will go back on.
I have had to cut the membrane with a knife in the hope that some good strength tape will hold it back in place, and I can see the lock :-)
Now what? It is a sealed unit, all the pulls pull but nowt happens. Disconnected electrics but a bit stumped. Any hints? Do I start to dismantle with ample use of a hand held mirror to see if anything broke.
Too dark to carry on now, so will update next spot of daylight I get free.