For a dead PC (by the way this is well discussed, google "The Dead PC") you wait for it to really dry out and the re-test. If it fails you downsize the machine like you read in your research to as few parts as you can. If the 4 parts don't stay on, it's one of those parts.

If the least number of parts stays on, you power down, add one part and test.
Keep adding till done or you find the bad parts.