Many states have "lemon laws" that may be used to force the manufacturer replace the entire vehicle or refund all of the purchaser's money, if the dealer has been given sufficient opportunity to remedy a defect without success.
The laws are complicated and vary by state jurisdiction, but if you tell me the name of the state in which you purchased the vehicle, I can try to find the relevant statue.
You can also sue for breach of express warranty, on the theory that the manufactuer provides a warranty for its product and the failure to remedy the problem is a breach entitling you to damages for the lost value of the vehicle -- which would probably be considerable, in view of the fact that every vehicle on the road is expected to have a working radio.
Ultmately, you would need to hire a private lawyer to sue on your behalf.
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Retired (mostly)