Yup, I'm coming to the same conclusion; LCS dead. Everything points to it, not least of all the peculiar gurgling sound it made when I laid the tower on its side and booted yesterday afternoon...

Oh well. I'm not going to muck around trying to refurb it, it looks overly complicated and not foolproof so I'll just strip it for parts and toss the carcass. Bummer, but I'll pick up an air-cooled G5 soon enough!