K790a Coverage Problems

[Longly]

Hi i'm new to this site and i'm looking for help. I have K790a unlocked and i believe debranded, the phone was originally locked to a service provider i got it unlocked but when i use the sim card of my new service provider it tends to loose coverage and when i search for a provider i get the option of the old provider i'm not sure what to do some one any one has any ideas

[SeaMonkey]

If your phone is debranded you haven't any icon from old operator,but if your phone is just unlocked - you have (maybe that is problem),so if you have that icons you need to debrand phone.Use this tutorial XS++ 3.1 Guide-Flashing, Customizing, Recovering - Top Sony Forums and when you connect your phone to XS++ post log here without IMEI number