I know this is a bit late, but have you tried disconnecting the hard drive then attempting to boot up the PC? If the PC stays on (it'll just display an error message on screen as no Hard Drive will be in the machine), then try putting a different hard drive in the PC and see how long it stays on for.
As for the "click" sound. That's actually fairly normal when the power is immediately taken away and doesn't necessarily indicate hard drive failure. You can replicate this sound yourself by holding the power button on the laptop until it switches off (kills the power immediately).
EDIT: For some reason I skipped over your most recent update simply because it was written in a different font... glad to hear you fixed it!