Service required i live in south texas and about every 2 hours it says cal. then service required rest same thing take it down like 15 min it works fine for about 2 hours

The problem never happens when it's cool or cold
my problem always happens when i turn the unit on, not while already riding/driving out of the blue

i believe the problem might be from the unit getting hot from being in a car, or on a motorcycle, or in a jacket in the hot sun then powering it up while still very hot, some kind of overheat circuit

find a way to cool it off, ride a short distance with it turned off then turn it on or...

also take the 8500 in you right hand and tap it in you left hand 3-5 times, it should start up and be fine. this doesn't have anything to do with temperature but i've had luck with it

good luck