I had a similar thing happen in my '01 GrandCaravan ES steering controls (radio/cruise) years ago. All controls went dead one day. Since it was under warranty, I made a appointment and brought it into dealer. I was informed that the "clock spring" went bad in the wheel and had to be replaced. That work was then done which restored all steering wheel controls back to normal.
Well, now it's even worse. It actually started working again today. If I can't recreate it for the dealer they can't do anything. And of course then who knows if it will continue working, or go out again some time after the warranty is up :-(