What would cause all of the audio to fail?

Yes, I took the neg cable off the post for about 15 minutes and the audio worked after I re-connected the cable. Thank you! The dealership was going to charge $120 just to check it out. Just FYI, I found out afterwards, there is a reset button in the upper left corner of the stereo faceplate. You can use a paperclip to reset the stereo. Really? The Hyundai service people don't know about these two fixes for this common problem?

Excellent! I'm glad it worked out for you with nothing out of pocket! Also, thank you for the info, I'll actually use that to write the problem so other owners don't have to go through this same issue.

You are very welcome! Yes, I guess this is a common issue. Sounds like Hyundai planned this type of required repair. This is the first vehicle I've ever heard of where the speakers fail, and oddly enough, there is a reset button designed into the system to fix it. How weird is that? The worst part in my opinion, is it was going to cost me at least $120 to have the dealership find out what was wrong.