I had a situation where I didn’t have the iLO virtual drives for an HP server. Whomever installed it, didn’t apply the iLO license.
After I installed the proper license; I was rewarded with:
iLO “Remote Console is unavailable. It is already in use by a different client”
Tried a few things but nothing worked. The iLO was simply locked.
You can force it to reset. On the top level (this is for iLO3), look for the diagnostics link under Information. Click the Diagnostics link
Look for the Reset button. Click it and you will be tossed for the session. Wait about thirty seconds and login again.