PowerBook G4-17inch (no sound output or input)

I noticed I no longer had sound a couple of days after I upgraded my OS to Leopard (not Snow Leopard just Leopard). I took my computer to the Genius Bar and they tested both the input and the output and suggested that it was the soundboard (they thought the OS upgrade wouldn't cause a problem with the sound). I ordered a new soundboard and installed it but I still don't have sound. If anybody has any suggestions on what this might be I would appreciate it. My next step unless anyone has a better idea is to reinstall my old OS and see if the problem is still there. Thanks in advance for any suggestions.