I appreciate it's a bit late for you, but I had the same problem, and the solution is actually really simple.
My lever appeared jammed locked. I had to wind down the window and open the door from the outside. The central locking still locked the door, but unlocking the system only caused a flicker on the lever. I spent an age looking for help on the internet, but no luck.
Thankfully the solution takes 5 minutes, 2 people and is fairly obvious when you see it.
Wind down the window.
The locking mechanism will be visible just below the internal window trim.
One person needs to open this gap (where the window was) gently pulling the internal door panel trim away from the external panel, only about 1cm.
The lock mechanism is a cable with a rod on the end. This rod sits into a socket (in a ball and socket mechanism). The rod can migrate upwards out of the socket, and get jammed.
Use a long screwdriver, put downwards pressure on the rod, and guide it back in to the socket.
Thats it, the lever should work.