I know it's too late, but I would have suggested to never start the car in the first place.
IMO you should've pushed it out of the water, that way you'd never have had to run power through the cars electricals, and just let it dry and everything would be fine.
Subwoofer breaks by shorting out, can't short out if there's no power.
Anyways, best of luck with the situation, I'm sure it'll be fine, the same thing happened to my Mom's old Tempo, we just pulled the carpet back and let it bake in the sun.