Just stress tested GPU/CPU, seems like the problem isn't really related to hardware itself.
Now I'm pointing into display, but since there was no physical damage. There was no issue under stress test, no errors pop up after diagnostic tool used on startup. It could be:
Display
Connector in display/motherboard
LVDS again?
Taking MB to Apple will result that they will charge me $800 for screen/gpu replacement. Keep in mind that those displays aren't produced anymore (not looking for Chinese copy).
Same MB Pro in good condition cost around 500-600 USD.