I had this message on my IIIsi so I had a spare
input card. Replacing that brought it back to life.
It was a network card and I wasn't network setup so I bought
a parallel card from ebay. It was also working.
Not fancy trouble shooting but it got it running again.
I believe I still have a number of IIIsi parts around.
I used some pieces on a 4si that I used now ( I think
mostly the duplexer ).
Dwight