Looking in the Bentley manual for the e36, it says
"After deployment, the detent pawl in a rollover protection cassette can be retracted using the special tool in the tool kit, fitted to the screwdriver handle. The rear seat headrest needs to be raised for this procedure"
I have no idea what this means, but from the diagram it looks like you get to it from behind the rear seat back.
fant dette på nettet. men har du ikke den "dingsen" i verktøy kofferten må du nok på bmw for å få det reset.