That sounds familiar. The hex driver goes into the hole where it will engage the hex bolt that is a captive part of the airbag.
Unscrew the first, turn the wheel a bit to get to the other, repeat the process, and ease the airbag out of the wheel before disconnecting the cable.

Sorry, but I can't remember the size of driver you need - from memory I think it is about 3-4mm across the flats.