Switched out logic board. Now display backlight won't work.

I was having frequent kernel panics with my 2010 MacBook Pro 15 inch. Thankfully my friend has the same computer and let me use it for parts. I replaced the logic board but now the backlight doesn't work (I can see images on the screen when I point a flashlight on it). Do you think this is a problem with how I reassembled it - if so what can I do? Or is it likely.a problem wit the new logic board I got from my friend?