"The power input for power supply 1 is lost"...

I'm managing a PowerEdge M1000 system.

It has 6 power supplies. 1-3 are plugged into an APC UPS, and 4-6 are plugged into a *second* APC UPS.

Today, when I checked the system, it was complaining that:

    "The power input for power supply 1 is lost"

    "The power input for power supply 2 is lost"

    "The power input for power supply 3 is lost"

So, I checked the UPS, and the UPS was off. I'm not sure if it was due to a power failure on that circuit, an over-temp, or if someone came in and turned it off, but I was able to power it on and it came right back up.

The problem is that the CMC is still telling me that the inputs for supplies 1-3 were lost. The UPS they're hooked to is showing no load on it. On the back of the M1000, on the power supplies, the green LED next to the AC-plug icon is ON, but the LED next to the power symbol is OFF (on supplies 4-6, they're both on). Now, if I pull the power cable out of supply 1-3, that single LED *does* go out, so I *know* they're getting some kind of power from the UPS.

So... how do reset the supplies so that they start drawing power from the UPS, again?