I have had a Sony HT-DDW830 for many years, my kids have pressed some button on it recently and now no sound is coming out. The display panel keeps saying 'UNLOCK' so does this mean they have somehow locked the sound??? Im reading through my manual and it doesnt say anything about this problem. I pressed the master reset button and still no sound, still saying 'UNLOCK' anyone know what magic button to press to fix this problem????