A database started up by CRS successfully, but you can’t connect it by local sysdba “sqlplus / as sysdba”, however tnsping or connect with connection string “sqlplus system@prddb” works fine.
Later, you tried to start the database alone manually, it works fine with both connection method.
You inspected every crs log and alertlog but it look seems fine.
Oops, why it inconsistent?
When clusterware trying to startup your oracle, it’ll use $ORACLE_HOME/bin/racgwrap , so make sure your system environment setting is same as the ORACLE_HOME setting in racgwrap script.