Car was in a flood, need advice.

It may be the computer but it likely will be more than that depending on how wet everything got. What does your insurance have to say about it? I would also check for water inside the engine and transmission and your brakes may be compromised too.

Insurance is a no go. Just had liability. The cars at a dealership. Said water got in to everything. I just need to know what im looking at cost wise to fix it, or what the best course of action would be.

That is a value call only you can make. I suspect that if you fix one thing another and another will come up and you may easily end up exceeding the value of the car when you are done. If water got into the interior then there can be mold issues and odors to deal with too. If you can get a complete estimate to fix everything from the dealer that might help you make a decision.