Simple question: I am about to upgrade to 3.5.1. from 3.5, Do I have to reset my AppleTV to factory settings before installing this update or I can just create my USB Flash, shut down the ATV, insert the new USB key with 3.5.1 and restart?
Nope, if you are already at aTV Flash 3.5, you can just create a 3.5.1 USB key and patch it over the old version.
Thank you madcran. You just saved me a lot of time! 