I’m not really aware of any voodoo to easily change node names. I think it would need to be done on the other nodes in the cluster which is kind of risky. I think the best solution would be to use cbtransfer to copy the documents from the database files on disk on the ‘dynamic’ node and into the remainder of the cluster.
You can find cbtransfer in the Couchbase bin directory:
$ export PATH=$PATH:/opt/couchbase/bin
$ cbtransfer couchstore-files:///opt/couchbase/var/lib/couchbase/data/ couchbase://<ip-in-rest-of-cluster>:8091 -b <bucket-name> -B <bucket-name>
Note this will also copy all of the replica data from that node. Since you were in a position to just shutdown a node without failing over or rebalancing I assume there was no traffic so this shouldn’t cause any issues as the replicas would be up to date. If that would be an issue then you can use the vbucket flag ‘-i’ to transfer each active vbucket one by one. You will need to failover that node (and rebalance) before you do this.
I recommend that you make a backup of the working nodes before you do this.