Keyboard doesn't work on Access Virus Kc - Need Help

  • Hello, I have a problem with the keyboard of my access virus kc. It does not interact with the sound generator and none of the keys on the keyboard work. But the sound generator still works (by pressing the edit and sync keys).

    I have read several times that I should downgrade the os to the oldest version (which I did but the problem is still there), that I should try to replace the 4mhz crystal on the keyboard board (which I did but the problem is still there), I also replaced some capacitors (not all of them) and same, the problem is still there. Should I continue to replace the capacitors? Could there be another component that could be involved...? Thanks for your help.