SAMSUNG BLACK SCREEN PROBLEM,STARTUP SOUND INDICATES POWER UP

MY SAMSUNG LN -S6251D IS GIVING ME THE BACK SCREEN PROBLEM NOW I CHECKED THE CAPS AND I FOUND 2 BULGING A LITTLE BIT . REPLACED THEM AND NO DICE . WHEN IT POWERS UP THE BACKLIGHTS COME ON BUT IM GETTING A BLANK BLACK SCREEN . I GET THE STARTUP SOUND AND NOTHING . WHEN I HIT THE SOURCE BUTTON THEN CHANNEL UP OR DOWN THE BACKLIGHT SEEMS TO TURN FLICKER OFF FOR A SECOND LIKE ITS CHANGING THE SOURCE . I NEVER REALLY PAYED ATTENTION TO IT IF IT WAS DOIN THAT BEFORE BUT I NOTICED IT WHEN TRYING TO FIGURE OUT WHATS WRONG WITH MY TV ...