Oracle client throwing ORA-12541: TNS:no listener
Could it be that you have started the listener process as root? I can see you are trying lsnrctl status as user root, so please make sure that you start the listener process as the oracle user, and then start the database (also as the Oracle user)

Also if you get "Connected to an idle instance", this means that you are connecting to an instance that is not running, or you have set the environment wrong for connecting to the instance you want to connect to.

Make sure you have the Oracle software directory in your path, such as /u01/app/oracle/product/11.0/dbhome_1/bin

and ORACLE_SID set to the database instance name.