From another older IBM 5110, I determined that it has a bad Display card (it has components from 1977). It does partially work. We haven't yet isolated down the specific issue. The test system I am using here does startup fine with its own original Display card. I can also place all the cards from this working 5110 into the older 5110, and that older system will work as well. This is how we know the problem is isolated down to some component on this specific Display card.