Well, i've decided to try to approach the solution myself.
Since flashing to custom ROM(whick does'nt exist for this) would debrand it, then i thought that maybe changing some files from retail version dump to the stock version would do it.
But i've searched the net for a retail version system dump, but have'nt fount any.
So anyone have a retail version dump or can make a dump? It does'nt necessarily have to be for same model. I think those carrier files are about the same for all.
I would compare the files and see if i can debrand this
For some reason, it appears that all other than 4G is working without any modification. I just needed to type APN settings manually.
All this time i though that everything is blocked, but appears not. But i still want the LTE/4G to work.
Now i've found out that maybe editing build.prop file would do the thing. So far no results when i tried to change few lines related to Verizon.