There seems to be a lot of misinformation regarding Tesla disabling salvage/ totaled cars. Maybe it's a matter of people using similar terminology to describe different things but this is not a thing that's happening. Tesla isn't shutting off cars simply because they've been salvaged. There are two things you can worry about Tesla doing to your car, both of which are going to be the least of your worries:
They disable the onboard 3G/ LTE radio - This is an easy one to fix. Simply tether the car to your phone and boom, back in business.
They disable supercharging - And honestly, who cares?
At this point I'm sure that's the least of your worries.
They're not going to make it so the car doesn't drive though. There are very few people that have had salvage cars and gone through that whole process first hand with Tesla. Everyone else is playing a game of telephone and every time I see someone post about what a salvage car does/ doesn't get it's a more unbelievable claim than the last time. I'm waiting for someone to claim that if your car connects to the internet Tesla will send a unicorn via SpaceX to cut the fire safety loop. In my case they never disabled the 3G radio and as far as I know, the new owner isn't having issues with it either. Supercharging was disabled though.
The good news is that these cars seem to be relatively straightforward as far as design goes. Aside for the motor and battery they are as simple and easy to diagnose as any other car, maybe a bit easier because you don't have a giant engine up front around all the components. So it's easy to get in there and see what's doing what or
not doing it.
Now then, with respect to getting this car fixed, depending on how much you've budgeted to fix it and how much you've paid for it, you might consider going through Tesla's re-certifcation process. From my talks with Tesla's body shop, the recertification process is simply to verify that the frame is not damaged and that frame repairs (if present) were properly performed to Tesla's specs. They require the car be torn down and 30+ pictures of very specific components are sent to Tesla.
If this car is verified flood salvage and clearly was not in an accident, you might have a really easy time getting Tesla to re-certify it since there's no frame damage for them to look for. The process costs $1500 and if the car passes they'll re-enable supercharging and your onboard 3G radio. The important thing here is that they'll then service the car. So in theory they could read the faults, pass them on to you and you can start chasing them down one by one. I'm not sure how that works in practice though.