At first excuse my language just plz try to keep up with me to get help
So I bought an used S9 plus Duos, inside its G965F...software info, build number its also G965F,, outside on the back G965F made in Vietnam,,, i discovered that's there is root and its on February security patch i tried to unroot it using Odin,,,the where i discovered its G965N!!!! Tried to continue by downloading official g965N firmware (pie 9) ... when the device restarted after using odin the phone working or showing just one sim even it was working just fine and even I used pie firmware its went back to oreo!!!
Plz ... Biiiig plz I need advices and solutions,,, I want to clean the root, I want to get updates ... and I want to get both of sim 1 and sim 2 work