All lights flash like crazy on powering up; diagnostic says "turn power off & on"

I have an HP aio 7710, actually, and today i unplugged it for awhile. when i plugged it back in (it plugs into a power strip that has a surge protector, btw), the display flashed up the normal "self-test" msg for a couple seconds, then all the LEDs went nutso, all flashing very rapidly, and the display said "turn power off, and on again." well, i tried that, but it wouldn't actually turn off--it would only repeat that same cycle again & again. i tried unplugging & replugging several times; same thing. is there any sort of "reset" button or procedure for this, or am i screwed? Thanks!