Replaced glass screen/digi. now my screen is black?

I replaced the broken glass on my iphone 3gs, screen replacement went fine but i accidentally powered the phone on while i was trying to pry the old glass screen up. Now the screen lights up but its all black? i tried to lift the motherboard off the battery then put it all back together but no luck. Any other ideas on what i could do to fix it or if i took it to someone could they be able to fix it. Everything still works, im still getting text messages and phone calls i just have no screen!