This component is a crystal oscillator.

ShovelKnight wrote:

This component is a crystal oscillator.

Okay, so that's not the component that's failed/need to be replaced. Thanks for that, any information is good. It seems that finding a schematic for a motherboard this old is hopeless (Google helpfully shows me the manual when I search for a schematic), so I'm hoping one of the old school techs who post here can clue me in on the fuse or diode that has failed.

So I think this is an example of my problem, but without a schematic I'm lost.

https://www.youtube.com/watch?v=S9pO-S9VvLg

I have one of those boards, but your picture is too small to diagnose anything.

I chose that image because I was hoping that cylindrical component next to the CMOS battery was a fuse. Apparently it isn't, but there's no visible damage to any component. But I can take more photos tomorrow.

Here's a nice image of the CMOS battery area I found on the web. https://i.imgur.com/xeGTqBH.jpg
And one of just the board. https://i.imgur.com/QTb1Ouo.jpg

Follow the circuit, starting from the pin that shorted to ground. Check every diode, transistor and resistor in the area. The datasheet for the southbridge should be available on the net, check to see if the battery voltage reaches the corresponding pin of the southbridge. Do that with the board powered off and use a needle probe, care not to short adjacent pins.

As it turns out, correlation doesn't equal cause and effect. I pulled the board out of the case and began poking around with my meter, and I couldn't find 3 volts anywhere. I finally checked across the posts where the CMOS battery holder comes through the PCB, and had no voltage there! It turned out that the negative side of the battery holder had a tiny bit of corrosion that was insulating it - with three volts, it doesn't take much resistance to break the circuit. I scraped it off, and all is well.
This is a big relief, as I bought this board for fun and nostalgia, and it came up for what is now the bargain price of $67.00 shipped. The only one listed right now is priced at $145.00!