I also successd to flash old version and UNLOCK for 709SC 02.2007
but cannot use WEB and MMS(softbank JAPAN), too...
by the way, I downgraded to 'V709SC_FK2' version and UNLOCK.
if i downgraded to 'V709SC_GB4', it falied UNLOCK.
'V709SC_GB4' is new version? (02.2007 ver.?)