I'm sure this has been discussed to death but every "tivo won't boot" thread I come across is about being stuck on the "Welcome..." screen. Mine won't even get that far. The TiVo has power, but no lights. If I unplug and reseat the power cord (from either end) the lights on the front of the unit flash briefly and then go out again. Nothing ever comes up on the TV itself. Suggestions? My first thought is a bad power supply but I don't have another one here so I wanted to ask for advice here before buying one to try.