Are you certain it is 100 percent as you described: works on AC and doesn't work on DC?

Or is it just intermittent in both cases?

Or is it just that it doesn't like booting up when it's cold (i.e., in the car)? Cold temperatures make metal contacts shrink and thus increase failure rates for intermittent connections.

I believe it's probably an intermittent case based on a bad connection as described in the FAQ link you were just given. I'll bet the car/home thing is a red herring.