eMac won't startup, hangs at blue screen (with white Mac OS X box )

Finally getting around to troubleshooting start up problem with old eMac running (I think based on what start-up disc says, 10.2).
Repeated attempts at start-up consistently result in hanging up at blue screen (with white box showing Mac OS X and a blank start-up bar), going no further.

1. won't start up from start-up disc, I don't hear the optical drive spinning up (makes repetitive noise, but never gets to spin up sound)

2. I am able to access the HD in TDM, I ran disc repair on it (Disc Utilities-DU), after disc repair was complete, DU said the HD was fine (I did not run verify initially so I don't know if there was actually anything wrong with HD to begin with) After running disc repair, there was NO CHANGE in start up hanging.

3. Attempted to start up in safe mode, did not respond, the initial start up process did take a lot longer like you'd expect in safe mode, but end result was same-hangs at blue screen

Any suggestions as to what to do next?

Check your serial number. Apple had issues with some eMacs.

https://discussions.apple.com/thread/1732741?start=0&tstart=0

Since they are so old the link is no longer valid in the thread. But it's very possible that you have one of the affected eMAcs.

my serial number starts with G3, so doesn't appear to be the included logic boards. This sounds like it is a unique start up issue to eMacs. I'm just wondering if there are any other troubleshooting techniques that can help to narrow down the culprit. Would be nice to determine if SW vs. Hardware, as it's probably not worth my time/trouble if it is a hardware issue on such an old machine.
Thanks for the suggestion & link.