I might be able to shed some light on this for you, when you send your console to get repaired, the repair process means that they have to test the console before sending it out, that means running a propitiatory tool that checks the hardware, the tool will most likely detect a problem with the nand, there is no way a company would repair a console and send it back out without testing it for more problems, it would cost them more moneyto send it out only for the customer to send it back