No video to internal display - how to troublshoot?

My wife's macbook hit the floor about a week ago, and since that the screen isn't working. It works fine with an external monitor and everything passes 100% using Apple Hardware Test. I've already used a flashlight to see if it's just the backlight, but it has no video at all.

At this point I'm about ready to replace the whole screen/lid, is there any way to know for sure that's the issue before I do?

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Edit:

Thanks all for the input, it was a combination of things but it's working again.

I forgot to mention that I'd already reset the PRAM/NVRAM and re-seated the LVDS connector, but I forgot to reset the SMC as Ahmad suggested. Resetting SMC brought back the backlight but not video. I double-checked the LVDS connector and re-seated again, and we're back in business!

There was a fleck of something on the pins of the board connector (not the cable) that I brushed away - none of the photos I took show it well enough to know if that was anything more than dust. It seems more likely that it got jarred in the fall - even though it didn't hit very hard, it was on the left edge where the LVDS cable is - and I didn't re-seat it correctly the first time.

Thanks!