What do I do to rescind the offer and get my money back?

That depends on the laws where the vehicle and seller are located. Generally speaking though by putting down a deposit you have entered into a good faith verbal agreement to buy the vehicle. Verbal agreements are usually legal and binding. Also, generally speaking, the selling Dealer has 30 days to issue a refund, if they're going to. You can talk to the local Office of Consumer Affairs, where the vehicle and selling Dealer are located, to find out what your options are. If you decide to take legal action just remember, you have to go there and you have to prove that a salvage title history was never disclosed to you. Maybe they didn't have to. That, again, will be determined by the laws where the vehicle is located. Jim