I'm sure you have ruled this out, but perhaps it was a power surge? I have repaired power supplies with bad components apparently caused by power surges. I don't know if there are any provisions for surge protection in the RioCar itself, but have you checked to see that the RioCar functions properly from another power source? If it doesn't, that's probably what happened.

I don't think being in the car would cause it, assuming you are infering high temperatures as the culprit. The components should all be rated to withstand far greater temperatures then you would encounter in the car, unless of course you were parked on the sun .

Stu