So I changed the rear drivers side door after a fender bender, pain in the dick to get all the wiring sorted etc, now the door won't open from the inside or outside (it worked for 1/2 a day)

Pulling the inside handle unlocks it (moves the unlock thingie up), unlocking the car from the fob unlocks the lock too. I got the door card off with the door closed (was a bitch), I can look in and see the mechanism, reaching in there i can move something back (same thing as pulling the outside handle), does nothing.

Anyway for me to reach in there and unlock the door? I having working mechanism on the original door I can replace this one with if I ever get the door open

 

You can use something long and insert it down inside the door from the removed rubber window channel. Its kinda a pain, but doable. I had similar issues as you, and mine turned out to be a previous owner incorrectly installing the door latch mechanism (I think they used a sledge hammer)..Things were bent inside the door including the latch mechanism linkage, I straightened out everything and bench tested the latch and reinstalled and all good.