Why is my Display backlight not working

So I removed my display awhile back because it was cracked, I got the new display and tried to use it to find the backlight didn't work. I took it to a Repair shop and all they did was replace the display assembly with a 2010 model, ripped off the WI-Fi connector heads and gave it back saying they couldn't fix it. So with my budget of 180$ i bought a new motherboard to find the backlight STILL didn't work. So I returned it and recently got a whole display assembly, new LCD, LVDS, and Backlight. Still nothing. So it must have to be a blown fuse on the original board. Even though I don't know why the second one STILL didn't work.

Any ideas of what to do? I'm seriously running out of options and eBay is not helping.