I'm not 100% sure how to disconnect the battery. I can't see a screw or clip on the + terminal. It says in the manual that systems like the electric windows need to be reset after disconnecting the battery, although it doesn't state how!
Through a series of random pushes on the boot close button whilst it's opening/shutting, I can sometimes manage to get it to retract all the way. I then keep the boot close button pressed for a long time, although it doesn't seem to stick.