So wait a minute (if you're still around.) Did you "reset configuration data" or restore optimized defaults in the BIOS? These could be two very different things. I have never seen a "reset configuration data" option in a BIOS. -- Update; I take that back. This option was in my old old pc 13 years ago! (I hunted around and found a screen shot of it.) But I was too inexperienced to understand what it did, until now.
It's funny because while reading your progress I was thinking: I wonder if he tried a hard boot -- maybe even pulling the cmos battery and resetting the BIOS. That's essentially what you did! But they had a nice option for it right in the program. (And they removed this from most computers, why?)
So for future readers with almost any hardware problem preventing startup: try a hard boot first. Do this by shutting down and unplugging the computer. Press the power button for 10 seconds to discharge it. Then wait for 30 seconds (could wait for 5 minutes to be sure.) Plug it in and reboot. This a very safe option and won't hurt a thing.
If that doesn't do the trick try pulling the Cmos battery. Power down and unplug and discharge again. Unplug the monitor too. Open the computer and find what looks like a watch battery on the mother board. Gently pop it out and wait 5 minutes then put it back in. (Watch out for static! Try rubbing your hands with a piece of fabric softener beforehand. This is why I say unplug the monitor.) The Bios will be reset when you boot up. You may have to set up some stuff again. So try keep a record of what the settings were. The link below says use your cell phone camera to take pictures of the Bios! Good idea.
Here is some good info from: http://www.pcbuyerbeware.co.uk/BIOS.htm
"The Reset Configuration Data BIOS setting
Resetting the BIOS itself (dealt with further along in this article) so that the entire BIOS is reset must not be confused with its Reset Configuration Data setting (shown in the second image from the top of the page) that resets its hardware configurations. That setting is enabled and the BIOS resets what the BIOS knows about all of the hardware components and peripheral devices (printers, etc.) and then disables the option so that its isn't repeated with every system startup. All of the existing hardware configuration data is erased and then replaced, giving a fresh start that can resolve many hardware misconfiguration problems.
The following problem is the type of problem that can be resolved by using the Reset Configuration Data setting in the BIOS: "I was changing the screen resolution on an older Intel Pentium III computer running Windows XP Pro when the screen went blank and said, 'not supported, 87Hz.' Only the first boot screen appears, which allows me to enter the BIOS, otherwise the screen remains blank."