I haven't seen any Brazilian ROMs and I'm not sure if flashing another region would affect 4G reception or not.
Your best bet is to try via the LG PC suite (link with tutorial in my previous post) or get the KDZ for you phoe from LG site:
You just need to replace the red text in the link with your IMEI (it is on the box or invoice).[/QUOTEFinally I managed to solve my problem, thanks a lot for your attention and for the tips.
Big hug and God bless you!