2010 Odyssey Head unit problems

Hi,
Thanks for a great forum.
I purchased a 2010 Luxury Odyssey in July last year. It has a HiTV HD4000 head unit. After parking the car on a hot day and returning, the unit didn't fire up. That was about 2 months ago. Since then it has come to life a few times on startup of the car; once the unit came to life while driving along. Everything in the unit functions OK when it does come to life. An auto electrician confirmed power to the unit and earthing via the car's wiring harness is OK.
My thinking is it may be a thermal fault.
HiTV don't support this model anymore which is disappointing. A new unit is outside my budget!
Has anyone had a similar issue?
Thanks,
Malcolm