I have a couple v2 blades that I can't seem to get working. Have a 750w PSU, wired in as described in OP. As soon as I paper clip the 24port on the PSU to power on, LED1 on the blade flashes 4 times then the PSU powers off and won't start up again until I undo and redo the paperclip. I have seen a couple other posters with similar reports, but no resolution. Same behavior on both blades.

Any ideas?

Also, tried 3 different PSUs, including one that is known good (driving current CPU). All same behavior.