Got it from Videohelp
WITH THE TRAY OPEN (I don’t know if that is necessary, but just what I did) PUNCH IN 9, 8, 7, 9 FOLLOWED BY THE DESIRED REGION CODE (“0” FOR ALL REGIONS). PRESS OK.
One on this site says
open tray, no disc in it, enter with remote 9999 followed by 0 and it’s region free!!!
Perhaps you got a later edition/firmware?