As with your previous thread, it's hard to give any concrete suggestions without seeing the Elasticsearch logs. I don't really understand why you cannot see them, sorry, but without them we're kinda stuck. I tried again to reproduce this (see my post in your earlier thread, a clean installation on a brand-new Ubuntu 18.04 instance) and sudo tail -f /var/log/elasticsearch/elasticsearch.log shows the logs we need.
Have you adjusted the logging config from the default? If so, can you put it back to how it was? There's certainly been some customisation because this node must discover master-eligible nodes [52.2.0.8] to bootstrap a cluster is not how an empty installation behaves.