LG C5 77" Turns Off After A Few Seconds. Worth Fixing It?

It shuts off by itself after a few seconds and before that, a line appears on the screen. The line color changes, I've seen it rainbow, red, etc...it seems to vary in shape and size. Also, if I leave the TV unplugged for longer, it does stay on for about 90 seconds before it shuts off, but it only stays on for a few seconds if I immediately turn it back on. The red light blinks 4 times also.

There is no physical damage to the panel, it just simply stopped working one day while I was watching TV. I already got the refund under warranty, so now I'm debating whether I should fix it and use it in another room. From what I read, it could be either, the power supply, main board or T-Con board.

Any suggestions?

https://imgur.com/a/ytFW73s