I've got the very same HDTV and had a similar problem. Try unplugging the TV and cable box, waiting about 30 seconds then plug back in. If that doesn't work then try to plug in a 3rd party device like a blue ray player, pc or game system and see if you get video. If that works then you may have a bad tuner board. If that does not work you will need to call in the repair guy. One of the most expensive replaceable components is the lamp so if you have already replaced that you might as well replace the board that went bad...