OFFLINE
Check your Networkcables, especially the cross over cable between both Cluster Nodes.
Check the Power cable and switch on the offline Node.
Wait until the Node is completely up and perform another Node Status Diagnose.
Failed Actions
Failed Actions can occure, if there have been cluster issues in the past.
This prevents a cluster failover, as those failed actions need to be fixed first.
The failed actions will be deleted from the history if you reboot the passive node.