Any markings or writing on the cards could be useful in determining what function they serve.

I'd remove the cover from the case then leave the computer in a window or other area known to warm for about a week.

If the machine does not show any additional signs of life, I'd strip it. Then leave the components to air dry individually and possibly help the process with a can of air or two.

After that I'd try a test bench boot. This would be just the mobo, power supply, video card, 1 stick of RAM, keyboard and a monitor on top of a desk or similarly flat surface. Fire that sucker up and see if it boots. If so, then I would reassemble the unit and enjoy using it.

I would also check the mobo for leaking / bulging caps.