Why are you trying to use start cmd at all.
You don't need it when running from the cmd prompt nor do you need it running in a batch file.
Also if you read the help for the FOR command you would see this very quickly.
To use the FOR command in a batch program, specify %%variable instead
of %variable. Variable names are case sensitive, so %i is different
from %I.
So your code becomes.
FOR %%G in (*.*) do (echo.>%%G:Zone.Identifier)