For LG BD390 the fix doesn't work once you have updated the firmware.

If you did the update, you can still go back to the firmware of Aug 2009 

(http://www.lge.com/us/support/product/support-product-profile.jsp?customerModelCode=BD390&initialTab=documents&targetPage=support-product-profile).

Once you have installed the past firmware, you can install the hack. Choose region 0 and save.

Then you can update again the firmware to the last release and the multiregion will still work.

Good luck