ML350 G5 not powering on after reconnecting power leads

[Andrew Slack]

PAT testing was carried out yesterday. ML350 was shut down and disconnected from the UPS (APC Smart UPS 1500). The UPS was also shut down and disconnected from the mains.

After testing was completed, the UPS was reconnected to mains, and the server reconnected to UPS (two connections for the redundant PSUs). The UPS was then powered on. Three other machines connected to the UPS powered on fine, but the ML350 was showing no activity apart from the LED on the ethernet socket. The green LEDs on both PSUs were not lit.

Followed all steps in the power on troubleshoot process, nothing worked, including connecting the PSUs to the mains directly with several different cables, reseating PSUs, etc. Eventually after a few hours the system power LED turned amber and the system booted perfectly.

Has apparently happened once before, and also spontaneously began working again after a few hours. Is this some sort of issue with the PSUs expecting some sort of wakeup from the UPS and then resetting themselves after a period?

Incidentally, only the lower PSU has an active LED now. The top one is still unlit. Is this normal behaviour?