Unity 680F failed upgrade on one node (0x6000014) / "Peer_Did_Not_Upgrade"

Hi, 

Trying to get a Unity upgraded from 5.3 to 5.5, and everything looked to be going perfectly until it started on the second node.  It failed to update and I'm not sure what I can do from here.  Uemcli won't let me cancel the operation, and when I resume/retry it, it just fails again.  What else can I try?  I'm afraid to attempt a reboot as I'm not sure what the status will be when it comes back alive.  This is not yet in production so anything destructive is just fine (as long as I can get the license file off first)
TIA