I have my 720 in for repair/replace under warranty. The guys were very supportive. To help them diagnose the problem, I ran a test on the 12V supply in my plane... 12.7 volts on the power plug... engine off. I also parked the plane in yesterday's 93 degree heat here in MA and let it sit with the 720 mounted on the RAM mount just in front of the top edge of the panel.
After 45 minutes, using one of those laser temp guns, the screen was about 128 degrees and the back case cover was 113 degrees. I plugged it into the 12V adapter and everything worked normally. I have an older AnywhereMap ATC that came with the plane that I can use as a backup. So I shipped the 720 back to AP on an RMA to see what's going on.
I wonder whether the RAM tablet mount I am using is blocking some vent holes in the 720 case and the heat is from the components themselves getting heat soaked on the first leg of the flight... rather outside heating from the sun. The 720 was NOT powered on during the 45 minute "out in the Sun" test
I've had the 720 since March 4th and flown about 30 hours with it. I has worked flawlessly during that time. The only thing differrent about the day it failed was that it was probably the hottest day I have ever flown with it.