In my job, I have needed to attempt repairs to instruments that have suffered from all manner of liquid spills. Sometimes you get lucky and sometimes not. If the PC was plugged in when the water rose, there is some possibility of short circuiting in two areas. The power supply maintains a control voltage if the power cord is plugged into a live outlet. Also, the motherboard battery will exposed to the water and leaking current. Because the PC tried to power up, something still works. How I would handle this is to do a complete disassembly of the box. Anything that's been under the dirty water needs cleaning. I would not hesitate to use distilled water on these parts as well as brushes to remove dirt and any corrosion. They need to be thoroughly dried. Sometimes a flush with anhydrous alcohols such as methonal can assist in the drying process but these have their hazards. Just be patient. Using warm air is not a bad idea. You might even remove the CPU and RAM to get into the nooks and crannies. Electrical connections need inspection for corrosion. If found, sometimes these can be cleaned. You also need a lot of good luck but, if it's already 1/2 dead, you may have nothing to lose. Be careful of the hard drive(s) as this is all that might have critical data. These are generally well sealed but do have a filtered vent. Reassemble and give it a try. If no go, hang onto the HD. You will want a chance to recover your data when you replace the PC. Good luck.
I have a Dell Dimension tower that sat in about 6 inches of water for a couple of days during Katrina. About 3 weeks after the storm I turned it on and it came up to the Dell splash screen (blue Dell screen). Is this a good sign??? I'm guessing I just need to reformat and I maight be back in action... Any suggestions or thoughts on this scenario???