Okay, played with this some more this evening:

I put the original HD in, on startup it spins up then stops.  I believe that the computer is looking for a startup disk, hence why it is spinning.  -but passes and spins it down once it determines it is not a suitable drive or unrecognized. But it is spinning up initially.  Just after that the screen goes back to the flashing ? folder.

I then swapped Charles's HD back in, (the 2.5" drive). I do not hear it spin up (but maybe it is a quiet drive)?? I know my laptop's HD is really difficult to hear.  I do notice that the top of the new 2.5" HD gets warm to the touch ...so it is definitely getting power.

I also tried restarting w/ extensions turned off (held shift key down).

I zapped the PRAM again.

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so tonight I didn't have any luck.  Next I will try that 7.5.3 patched boot up disk from a floppy.  Yet that may have to wait a few days, as I have some other work related things to tend to.  

as a side note, I have an extra motherboard that is bad, but some parts may be fine, ...i read that there is a "SCSI controller"?? Not sure what this is or what it looks like, but I could swap some hardware parts from my other motherboard if there are known parts that fail over time? ...so that is an option.  

any further recommendations welcomed!