When you say don't turn the ignition on until the dash is screwed into place, would this also apply to when you've had the steering wheel off?
I've removed the steering wheel on my astra coupe to replace the bulb behind the odometer but now the airbag light is constantly on and i think it might be because I turned on the ignition before everything was back in?
Any ideas on how to sort this out? Do i have to disconnect the airbag and reconnect it again?