Yes you are right ,
i will go for basic training .
SQL> startup mount
ORACLE instance started.
Total System Global Area 7535046480 bytes
Fixed Size 741200 bytes
Variable Size 3808428032 bytes
Database Buffers 3724541952 bytes
Redo Buffers 1335296 bytes
Database mounted.
SQL> alter database opn
2
SQL> alter database open resetlogs;
alter database open resetlogs
*
ERROR at line 1:
ORA-03113: end-of-file on communication channel