If the seller knew or logically must have known (that is, any reasonable seller under these circumstances would have known) that the appliances do not work but did not disclose that fact, and getting the appliances was part of the contract (i.e. they were not excluded), then the seller, by failing to disclose a known issue (i.e. by lying) may have committed fraud. So if this occured, you could sue the seller for the cost of new appliances. You'd have to prove in court that the appliances were part of the deal and that the seller either did or most have known that they did not work.