There is a mode which can be set to ‘disable’ the buttons, so that people don’t go messing with it.
I seem to recall there is a ‘magic’ sequence of button pushing which will restore it.
I suggest you just give IBM a call – that’s what you pay support for.
else, get the books out. There used to be one which dealt with all this stuff that was shipped, but its a couple of versions ago since I dealt with this stuff..