Remove the door trim and try to lock/unlock you my find the trim is stopping it, if it still does not work key or handle I would look at your door actuator they do seize up. You can remove it and clean them up and give them some lub.
I have attached some images, If you see the gold looking latch If i move that down the door does not open however if i do the same on a working door it works. I have a feeling there's something wrong with the lock but how can i get this out?
I think if you push down on the gold arm in picture 1 the door should open I think this is the latch release. It's been a while since I was in there on mine.
I would drop the window about 1/2" while you are messing with the latch Incase the window does not drop when you try to open the door it could break the glass.
Just to say - sorry, i can't really help as I'm not a techie type Mini owner - but i do sympathise.
My passenger door can only be opened from the outside (although you have to squeeze it reallllly hard!); although from the inside only my daughter can open it by carrying out a waggling pattern on the door latch, but my son cannot open it at all from the inside.
I've had it repaired three times and three times it's stopped working again. Shortly will be going for forth time lucky so I wish you well with your own endeavours!!
Just an update: I was able to pull on the interior door cable and was able to open the car. However the door only lock when pushed into the car, it appears when i try lock it with the key it has no affect?
Also the exterior door handle mechanism doesn't unlock the door. Does this suggest I buy a new actuator?
I should be able to take the lock actuator out but I dont know what im looking for after.
There is obviously a problem with the actuator so I would replace it with a new one. You can get them off ebay for around £65 but dont be tempted to get a 2nd hand one or you may end up with the same problem
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