My best answer here is to open an SR.  Depending on the configuration that was implemented prior to shutting down cluster, there may be globally visible objects such as distributed consistency groups, distributed devices and globally visible local devices which require communications between both clusters to break down in a graceful manner.  This is no longer an option.  The next best option may be to do a system reset.  Prior to configuring it, do the ndu pre-config upgrade.
In our labs in CA and NY we had originally configured a VS2 Geocluster running Geosynchrony 5.1.  The cluster was powered down for a period of time and the CA cluster (cluster-1) was repurposed.  I am left with the task of upgrading the remaining NY cluster (cluster-2) to 5.4.1.003.  No problems upgrading the management server, however when I attempt to install the firmware package to complete the upgrade, the ndu pre-check attempts to check the status of the remote cluster (cluster-1) and fails with:  "Could not find an active meta-volume at cluster cluster-1" and "Failed to retrieve remote management server version."  Does anyone know a workaround in lieu of resetting to factory defaults and rebuilding as a Local cluster as I am in a pinch to get this done ASAP.  I've tried every ndu start skip parameter that is documented, but no luck.  Thanks! 
Upgrade Geosynchrony on orphaned Geocluster