can't restart my ATV

My ATV continuously flashes fast and I have tried everything from the support options. I have it connected to my tv and ethernet and still can't get a connection to show me a menu to restart. Help? My screen shows a picture of the ATV box and a cord connecting it to iTunes. I don't know what cord that is supposed to be and I'm not sure why I need it all of a sudden. It used to work flawlessly and now I can't even get a menu on my screen.