Editing Country Group Code For LG 55LX6500-CA

[jagbogah]

Hi Guys, am unable to change the Country Group Code for LG 55LX6500-CA from China. I ve access to Ez Adjust menu in service mode but it appears the Group Code has been locked for access.
Has anyone got an idea to how to unlock it
I hope there is a way out and i appreciate any suggestion.
Many thanks.

jagbogah