hmm. I u running in SD or HD? Could be a problem with an hdmi port as well (My HDMI on my refurb didn't work, only got the audio)
Try running it in standard def, and then change the configuration settings in the dashboard. If that doesn't work, try using a different input on your tv.
If all else fails, I'd look into signs/symptoms of internal video card failure (though I'd be suprised as it seems it is passing the internal tests and not giving a light error)