I was trying to create a standalone ASM instance on a Solaris box. Where I started getting ORA-15150 instance lock mode ‘EXCLUSIVE’ conflicts with other ASM instance(s) error.
Checked processes at operating system level
$ ps -ef grep +ASM
oracle 20623 18975 0 06:28:02 pts/1 0:00 grep +ASM
ASM instance was not running. But there was an entry in /var/opt/oracle/oratab
Removed the entry & created the ASM instance.