[CentOS] OT: hardware, odd PSU issue

We have an HP blade enclosure for SL230s Gen 8. Went to replace the four PSUs in it, 1500W. Got them from one vendor, "refurbished"... and *none* worked. Returned them, and got them from another vendor, and *none* worked.

Something odd here. For one, the LED doesn't light up when I'm holding the PSU and plug it in. Then there's something I just noticed late yesterday: in the socket of the PSU, on the shorter side of the trapezoid, there are four copper strips, running from the inside out.

Anyone run into this before? Do these not power up, because they need some sort of odd power cord with something for those copper strips?

mark, befuddled