Backlight flicker and horizontal lines running down

I replaced the battery, keyboard and backlight last week a and a few days later the screen started acting up. First the backlight starts to flicker a bit at the top and then these weird horizontal lines run down the screen. I tried reseating the display connector and I can’t replicate the problem. It happens completely randomly and sometimes everything will be fine for hours. External displays work perfectly fine. Anyone experienced this before?