Question I have a samsung un55mu6490fXZA. Why is it not powering on?

[Duckgoosed]

I received this tv from a lady on craigslist. Got it for free! She said ever since she was doing some painting/sanding, a lot of dust went into the tv and it no longer turns on. Does not power on at all. Should i wipe the circuit board with rubbing alcohol? Perhaps blast it with compressed air? Any recommendations??

 

[Duckgoosed]

Just wanted to post an update. When i unplugged the cable shown in picture, the backlights turn on... So do i need to replace the power board or the main board?

Ok apparently I can't post photos. But it is the cable connecting the power board to the main board.