audio off message on nav screen Radio does nnot work. Cassete and Cd they do work. Help.

That's an oddity, I would return to the same Lexus mechanic and ask for further guidance since you were seemingly led down the wrong path. Hands on testing is required. That's the best I can say. I would ask: What did you replace? The display? The amplifier assembly? The Navigation ECU? I'm guessing the component you replaced was not a party to the failure -- it's another audio system component that feeds what you replaced. I'd strongly recommend getting some shop manual information to learn about the different components on board this vehicle.

Toyota / Lexus models inherently have problematic audio systems - just saying .. Perhaps the replacement is defective as well. Technical assistance - CRUTCHFIELD - 1-844-264-9462