The Oracle error ORA-00054 can be solved by executing as DBA the following query

select p.spid,s.sid,s.serial#,s.username,s.status,s.last_call_et,
       p.program,p.terminal,logon_time,module,s.osuser 
from 
       V$process p,V$session s 
where 
       s.paddr = p.addr and s.status = &39;ACTIVE&39; and 
       s.username not like &39;%SYS%&39;;

This will return the PID of the hanging process

You can then SSH to the server ruining oracle and kill the process

kill -9 PID