If the SMS software detects that a power supply is present but no power is
applied, then the SMS software will disable the power supply using the internal
(DC) breaker.      

To fix this perform the following:
1. power off the PS via SMS
2. turn off the AC breaker(s)
3. disconnect the power cord(s)
4. remove the power supply
5. await ESMD to detect presence loss
6. install new power supply
7. connect the power cord(s)
8. turn on the AC breaker(s)
9. tighten down the power supply screws last