Based on your postings, nothing you have done rules out overheating. Have you actually added an external fan to cool the receiver? As far as your temp readings after less that one day of operation, they are meaningless. It takes weeks of continuous operation for these temp readings to be really meaningful.Ok, my new receiver was working greate yesterday, and the temp was fine on it. I've been gone all day, and just got home. I went to turn the TV on, and lo and behold, this receiver is doing the same dang thing!!! This is really frustrating. What else could it be besides overheating, which it's not, or junk hardware?
Did you try unplugging the receiver for at least an hour and then see if it runs again?