In reference to your genius bar rep, they're quite often not more knowledgeable than general CSR and other staff at Apple Stores. I'd refer to many associates that Apple hires for the store as it being more necessary to have a "great smile" and be a salesman. So from my experience from Unix systems since the mid 80's, computers of varying OS, GAC & COMM/NAV tech, and so on is, unless this was a design that's been reviewed by an engineering team and actually inspected via specialized equipment, then for a device of this size, THERE IS NO WAY to determine that it's only a hardware problem. What some Apple Store employee or what you like to refer to as a "genius" >>> "salesman with a smile" who observed people returning them to one store is the most ridiculous basis for a diagnosis that I've ever read.