HP BladeSystem C7000 Onboard Administrator lost contact with ILO2 on a Proliant bl460c blade

A while ago we upgraded our HP BladeSystem C7000 Onboard Administrator (OA) firmware to the latest 2.60. A few weeks later we upgraded the ILO2 firmware on the blades to 1.80. All but one worked fine. The last blade would not communicate properly with OA. Nothing serious I suppose, but I'm always suspicious - thinking that small issues could lead to something horrible if not dealt with properly. Plus - it's annoying.

Symptoms:

• I could not initiate a ILO remote control session from the OA web interface (it would time out and say "Unable to perform autologon").
• The only way I could connect to ILO was adding a local user with HP Lights-Out online configuration utility (hponcfg) from Windows running locally on the blade.
• The configured ILO DNS-name would not register with OA.
• OA / Device Bay Summary would report "iLO name: [Acquiring]" and "iLO DVD Status: unknown".
• IML Log for the blade was not available from OA.

I tried all tricks I could think of:

• Ran a emulated eject/insert of the blade ("reset server bay XX" from OA CLI).
• Reset all settings on the ILO card to default from hponcfg.
• Rebooted the ILO card from hponcfg.
• Upgraded ILO2 firmware to 1.81
• Restarted OA.

However - what finally solved it was simple enough. I simply reapplied the 2.60 firmware upgrade again. Fair enough.