Grafana works for me - but the initial load takes a bit. Have you tried accessing the page again? You can always try restarting the Grafana instance by entering the following into a console session:
init GRAFANA!PROCESS
The Archive and ConfigurationCache folder will be important - note that the main reason the ConfigurationCache is important is simply because the openHistorian.db SQLite file configuration file is located there - you could move this to another folder, e.g., Archive (location configuration in openHistorian.exe.config). For diagnostics, the Statistics folder is a good folder to hold on to, but not a requirement. Also note that if you get Grafana working, your dashboards are stored in a SQLite file as well, by default /opt/openHistorian/Grafana/data/grafana.db. Here also, this file could also be relocated by changing its configured location in the opt/openHistorian/Grafana/conf/custom.ini file.