If JBoss is not started successfully (status remains 'starting' for a long time), you may have to wait until it starts up successfully or you can kill JBoss process (using its PID) and restart it again.
The following error messages show up when you try to start or stop JBoss respectively while its status is still 'starting':
Cannot execute action as another process is holding the lock.
Cannot stop service 'jboss' while in status 'starting'