I've only done this once & it was ages ago, but, IIRC:
Gently pry off the plastic cover of the door handle. This is the door handle you use to pull the door shut, not the steel one you pull to open the door.
Through a couple of round holes you'll see a couple of biggish screws. Remove them.
Once these are off & starting at the bottom VERY gently pop off a clip holding the doorcard onto the door.
When they're all popped off undo the little metal bar to the locking mechanism & the wire to the door.
Maybe someone else could confirm this is the correct procedure?