Seems a coincidence that multiple PSUs would die simultaneously, especially the hard core PSUs you get in Spondoolies gear. Is there a chance that a breaker has tripped, a cable melted, PDU died etc etc which is causing this? Tried swapping the power cables (and so circuits) from a working unit with one of the dead units?
.. they die simultaneously if it wasn't an internet breakout, but a power outage and all the PSUs were hit with a spike from the grid side. The toughest didn't die .. but the rest ..