Dear All,
Problem solved. I should replace the new file in the Media of installation, and not in the \Central\AS directory.
Looking at the command of the log, I assumed I need to replace that file in C:\Program Files\sapinst_instdir\SOLMAN71\SYSTEM\DB6\CENTRAL\AS\db6_update_db.bat
Corrct place to replace - Installation_Media - "WINDOWS_AMD64"
sapinst copies the batch file to \Central\AS every time you "Retry"
This was the mistake
Works fine now,
Thanks.