Elasticsearch won't start after plugin installations

Question

I installed MongoDB and Elasticsearch to my Ubuntu machine, mainly following this tutorial: https://coderwall.com/p/sy1qcw/setting-up-elasticsearch-with-mongodb

As the tutorial goes, after the plugin installations, Elasticsearch started not to start as a service (Either sudo service elasticsearch start or /etc/init.d/elasticsearch start outputs as OK, but curl'ing localhost on port 9200 gives ERR 7 or checking for the elasticsearch service, it says it is not running).

I am suspecting there might be a problem with $ES_HOME, ran into the a similar problem when installing plugins, it couldn't find the /usr/share/elasticshare directory, I manually locate the plugin script. Java version appears to be OK, if that might be the case.

Any suggestions?