Random Intermittent Backlight Issue on Samsung JU6800 LED TV

For the last few months I’ve been having what I assume is a backlight issue where the bottom half will go darker than the top.

It is completely random, sometimes will just flick on and off now and again, sometimes it’ll stay one way or the other for a few days. See: https://youtu.be/imiNzNXKkFc

It is on all inputs and the OSD, I’ve tried leaving it unplugged for a few hours and fiddling with backlight related settings.

After a while of intermittently occurring, it seemed to have stuck for good. So I completely disassembled it to investigated the boards, connections and LED strips. Everything looked fine, and of course it decided to just start working perfectly again… for a while. After a few weeks of working perfectly it’s started happening again!

Any inkling on what could be the cause?