Huawei p9 EVA-L09 appears lights grey.Seems to not connect something.

I need some help! Huawei p9 EVA-L09 single sim, after replacing display, appears lights grey . it seems to work but i dont see any thing on screen. I'd thinked that should be the connecter problem. That seems to not connect something but I checked all the connectors and I dont know what happened!! I controled all the parts and I don't know what should I do?

I tried with three different displays !!!