The power-on circuitry is fairly simple and does not involve any 100 pin chips. Probably a few of those tiny surface mount transistors.

There is a schematic of the circuit around somewhere, but I have no memory of where. With a little luck, someone else will come along and post a link. You may wish to start a new thread, "Schematic for IIci Power-on Circuit?"

I would also check that you have good continuity between the caps in the power-on region and the board pads.