When database is running and if you want to reset logs, Oracle will not allow you. It will say that, Only you can reset logs for incomplete recovery. Long back i got a problem with my backup script. When it is doing check sums i got errors. So i followed these steps.

SQLPLUS> alter system switch logfile;

SQLPLUS> alter system switch logfile;

SQLPLUS> shutdown imediate

SQLPLUS> startup mount

SQLPLUS> recover database until cancel

SQLPLUS> alter database open resetlogs;

Do an immediate cold backup

Hope it will help you. Good Luck