sqlplus / as sysdba is not connecting

cd /a01/arpkwcd1/oracle/12.1.0.2/rdbms/lib

vi  config.c

change dba group as needed

cd $ORACLE_HOME/rdbms/lib
rm config.o
make -f ins_rdbms.mk $ORACLE_HOME/rdbms/lib/config.o
$ORACLE_HOME/bin/relink all