Let me guess that the surviving node was not a master? Even if it was (and others were), you lost > 50% of your masters so it can't run an election, so the cluster can't recover.
Others may have more ideas, but I don't think there is a recovery path from here, as you can't get an elected master and without that, can't change things, find data, etc. No elected master = no cluster = no data
It would be nice if there were more recovery methods, such as to tell an old master-eligible node to consider itself the single master with its stored state, and let a recovery proceed from there with any existing nodes, etc, but alas, no one has built that yet, as far as I know.
Elasticsearch does a lot to protect your data, but once it breaks, it really breaks and has little in the way of tools or methods to recover even part of lost data (e.g. segment export, meta-data bottom-up rebuild, etc.) Some day (we used to have/build these for old DB/code systems). And maybe enterprise-level support has special tools.
Hope you have snapshot ... and others have ideas.