Firstly the SRS system. This is a stand alone system from what I can glean from the diagram, (there’s a bit of first hand experience mixed in but that might drift into opinion). I can see no reason to be too worried about damage to the controller, which is mounted under the switches. The wires when called upon to do their job fire a charge, which snaps back the seat belt, giving you the supplementary restraint. I’ve never had first hand experience with these so I’m unaware of what jollity follows one firing but if they were polarity conscious getting in wrong might have added an extra bit of excitement to your day.
What is causing that fault I don’t think is at the root of the cars failure to start, so let’s start with my favourite problem which exhibits similar symptoms.
Tucked down below the charcoal canister is the starter solenoid, the Lucar / Faston connector gets loose & grotty. Stuff your hand down there, have a rummage about & you’ll find it, even the slightest movement can return service & if this happens be the fault replace it. If it’s not, next time you’re under there replace is anyway.
With the SRS system check all contacts, including the rotary coupler behind the airbag in the wheel.
M