Node is displayed as unhealthy if the node on which the management console is running is stopped
If you stop the node where the management console is running, the node is displayed as unhealthy and the option to start the node is no longer displayed in the UI. (IA-37062)
Workaround:
Switch the management console to some other node before stopping the node.
If the node was stopped before switching the management console, log in using the management console IP address and in the shell menu run the run cluster start nodename command where nodename is the name of the node that was stopped.