6x6 lock install

[JC works water]

Hi, I have ground a door weld off to install the lock and rods. I was testing the lock mechanism,it seemed ok then I shut the door and it will not open.
The door skin is still off so I used a screwdriver to release the latch. It released half way and the door is still shut.
The button and interior handle still work but do not seem to be making contact.
I have been able to watch the lock mechanism work from observing from inside the car and can see where it passes behind the button rod which terminates in a triangle Piece of metal .
Everything moves but it is still locked.
Any help is appreciated before I cut the door latch out.

[JC works water]

I got the door open by using a tiny screwdriver and pressing the lock pin up a fraction. It sits above the latch  mechanism, which fastens to the door striker, which holds the door in place. It is around 4mm by 2mm and needs to be pressed up from the inside above the door striker. Easy to do once you locate it. An Allen key ground down would work also, say 5mm high on the ground side.
So now the door locks and works ok but upon unlocking the Lock pin( the above mentioned 4mm by 2mm piece of metal) does not return. A small push returns it effortlessly.

[JC works water]

The internal door handle is not engaging. Something must have come adrift.