PowerVault MD1220 "DC Power" Indicator not lit

Greetings,

I have an MD1220, and one of the power supply indicators is out.

The bottom indicator ("AC Power") is lit, so I know I have power coming in to the unit.

The middle fault indicator is not lit, so no problems there.

The top LED ("DC Power") is NOT lit, which seems to indicate the following:

If this LED is off, it indicates that the DC output voltages are not
within the limit.

The Modular Disk Storage Manager software has the following error:

Storage array:  Component reporting problem:  
Power supply module (Right)   
Status:  No power input   
Location:  Expansion enclosure 1 
Component requiring service:  Power supply module (Right)   
Service action (removal) allowed:  No        
Service action LED on component:  No   
Subcomponent affected:  Power supply  (1) 

So, while power is being supplied to the unit (it is plugged in) the MD1220 doesn't like it, and thinks it's not plugged in (even though the "AC Power" LED is normal).

So my question is, does this indicate that the power supply has failed and needs replacing, or could this be something else?

Note that this was all working correctly until I had to shut everything down for UPS maintenance.  When everything was powered up again, this issue presented itself.  I've tried plugging the power source into other sources (even direct into an outlet) and that changes nothing, so it's not an issue with the UPS or power source from what I can see.

Thanks,

Bill