Question ASUS TUF A15 green pixel grid on startup

Sep 17, 2020
I bought an ASUS TUF GAMING A15 FX506IU laptop a month ago and yesterday the screen started to show this green pixel grid thing on startup. It can be seen mostly on black. If i open google for instance it's barely visible(if maybe it not visible at all) Firstly i reinstalled the AMD integrated graphics driver then it disappeared for the rest of the day. Then when i start my laptop today it showed up again. Now i restarted my laptop a few times and gradually disappeared. Lastly i turned it off again and gone to have lunch. After that it showed up again. Done nothing and disappeared after a few minutes, totally. I tried with an external monitor through HDMI-->VGA and that screen was completely fine. I am not dumb for computers but never ever experienced this kind of problem. I already get extra RAM, HDD and new WIFI card(the original one is a cheap one and incredible laggy) for the laptop so i am a bit afraid of guarantee. I assume the problem is the screen or the ribbon cable but can't know for sure. Of course i already get off the back of the laptop to change the mentioned parts but never touched anything else(except battery connector). I hope somebody can help me, i am bit desperate what could be the problem or what to do. Mostly because now for instance it's working perfectly fine. Thanks for the help in advance
Laptop specs:
-Ryzen 7 4800H
-Nvidia GTX 1660ti
-144HZ screen(there is 60hz version i think)
-48wh battery(there is 90whr version)