There are a bunch of causes for a loss of video signal, ranging from disconnected/broken wires to failed IC chips. The only way to know is to open the unit up and visually inspect the cabling, solder joints and ic's for indications of overheating.
Since the sound works that tells you the laser is reading the disc and processing that part of the info. Seeing static tells you the inverter/light source is working. Don't know about your system but the systems I use at work state loss of video when a signal isn't present. I would venture a guess to a failed ic chip or cold solder joint on the main board.
In layman terms - door stop.