Winarills

I have a 2010 ES350 with Navigation and I have been noticing this behavior a couple of times. I drive home and all was working fine. Parked the car till the next morning and started to go out but dead radio. Restarted checked fuses but no joy. Without much time to lose, I drove on and 20mins later, the radio starts working. 2 months later same problem and unit came on 30mins later. Last week it went out for 2 days and just came back on this morning on its own.