All sound stopped (radio, blue tooth cellular, nav guidance, CD, voice command). Audio menu displays work, but no volume display and no sound settings access for base, treble, etc. Less than 10,000 miles. Any known reset commands, etc., that may fix?

 

Try disconnecting one battery terminal for several minutes.

 

Hold the volume button down to see if the system reboots.

 

Press the SOS button, it may respond with "Emergency Call Cancelled" and all your audio will resume.
It may also say "To cancel this call, press again" do so and this was not your original problem...

 

For those who responded with suggested self fixes, thanks. I tried the suggestions without result, and drove the 2016 RX 350 100 miles to my nearest dealer. Turns out the amplifier failed. I have a loaner Lexus for a week, while a new amp is ordered and installed. Dealer told me they have seen problems with Mark Levinson radios, but no so much with "basic" Pioneer radios - bummer. From seeing owners' comments from 2nd and 3rd gen Lexus, it appears the Mark Levinson radio audio failures are an ongoing problem. Too bad that Lexus' "premium" radios are known for more failures than "basic" Pioneer radios. I presume the amps are supplied by the same manufacturers as the radios. Happily, the Mark Levinson radio in my 2007 SC 430 has never given my any problems.

An aside, the "SOS" system uses separate electronics, and works even when the radio/amp that runs everything else fails.

Anyway, thanks to those who responded.