Hi Tom, You're right about the jumpers, as I was reading through your reply that was the first thing that came up tp my mind. But you are already well known with it.
Isn't there a function in the BIOS that says "Power on by usb keyboard " or something like an usb mouse?
That could very well be the solution.
By the way, the red LED is NOT lit while in sleep mode.
I hope you will be able to get it going, after all it's very nice to be able to turn everything on and off with one push off a button!