Oh wow... EPICenter 6.0!
In the past, when restarts didn't work I've seen success with saving the database files separately and uninstalling and re-installing EPICenter. If you try this, make sure you have your license key-- I'm not sure how to look that up at this point. Once it's installed and running on an empty config, stop all services and copy your database files back into the db folder and restart services (or the entire system). I don't think there is anything else to be aware of, but it's been 5 or 6 years since I've touched EPICenter.
The best thing to do is to contact your sales team and get a quote for Netsight/ExtremeManagement Let me know if you need help with that.