Hi... i have same issue and tried this many times.
Went to the store where i bought the phone.. but they dont want to replace it. They said its a software issue and just deal with this. Even i only have this phone for 3 months..
Sprint refuse to fix the problem and refuse to change my phone
I have a similar problem with my new Note 8. THere is a line (yellow line if white background) in my screen. Phone is about a month old.
Your idea of *#0*# is very useful.
When testing the Red, Green and Black background it is okay. But when testing the Blue background, there are two black lines in the middle of the screen (everywhere else is blue).
What should I do?
You have to call your phone carrier beside your phone is brand new.. its under earranty for sure.. i think all samsung new phones have issues .. or you can fownload tech expert app in google play they are helpfuk