I am using sony cdx-r6550 car cd player. It was playing fine and would not work now. I usually take the system off when I leave the car. This time I pressed the off button before removing it and it would not play again when i am trying to use it. i tried to meddle with the ATT and all buttons but no luck. When I press ATT button i can hear the beep sounds when i press the buttons but there is no display or sound. can any one please help. unfortunately I lost the user manual. thanks for your help.