on-board means "inside of A500". Make sure that you don't enable other options that make patching the ROM mandatory.
All those who are interested buying one of those cases: Make sure to get a case where the manufacturer has shown some level of thermal control. I only see closed boxes with no ventilation holes, and that's good reason to worry. Also, the materials used for those cases are not clearly specified: What's the flammability level, are the materials UL listed?
All this can be set aside if there's a product insurance involved.