my j7 2015 i have problem with display screen is blinking when i do low brightness whats is this ??

my j7 2015 give me very bad experience because afte 4 month it coming line on display at the time switch on phone line is coming and now there is new problem now there is i do low brightness then half display is on of what is this very bad samsung 

i have j7 700F i update last software form that day it has line on display at the time switch on phone line is coming than other thing work properly videos games all what is this only at the time switch on phone what can i do i go services centre the...

give Nougat to j7 2015 work fast for it

when will j7 2015 will get naugat update .it also popular give naugat update plz any one can tell me when it get ????