Rear door handle won't go back in

Apologies, this question is for a Mk1 Seat Leon but I'm not getting a response an any Seat forum.
 
I'm trying to change the rear door handle but I can't hook it back in, so it sits proud of the door. When removing it, the white plastic thing moved backwards and went click and is now sat behind a little brass lever that I can't get to move. I thought locking and unlocking would do it, but it doesn't. I've tried screwing/unscrewing the gold T20 torx screw again and pulling out the handle when doing so (which I think I should have done the first time) but nothing works. Any ideas? Photo attached.