I just thought I would update my original question even though I now
know that a keyboard is NOT required for the motherboard to power up and
show something on the display.
What seemed to be fixed as described above was not the case. (The fact
that the computer started working had nothing to do with the keyboard
being connected. It was simply a coincidence.) The computer did work
for several weeks and I thought perhaps it had been fixed, even though I
did not understand how. Suddenly it started displaying the same failure
symptoms that I originally encountered again. This time before taking
the computer apart I searched the web to see if others with the same
model of computer had experienced a similar failure. I found that many
had, and that many thought it was attributed to the power switch
daughter board used to turn on the computer. Again I don't quite
understand the bizarre failures since they changed in their symptoms,
but I decided to look at the computer again with particular attention to
the daughter board used to turn on the power. I looked for a poor
solder connection since intermittent failures are most often due to such
a failure based upon my experience. I did not see any poor connections,
but I re-soldered all the connections I could before reinstalling the board.
Again the computer worked and has been working for about two weeks. Is
it fixed?? I am not sure. It is working, and since there are others
that believe the power switch daughter board was the reason for their
failure, I thought I would pass on my experience.