The same thing happened to me -- it went on but shortly after went off and the led on the power brick was off. Luckily I realized that the cable at the back of the power brick just loosened over time. So if you are panicking right now if you trashed your rack, make sure the cable (into the power brick) is properly inserted. (I needed a good amount of force to get it in, even if it looks plugged, it might not be).