Screen problem

[Android Central Question]

Hello, after screen replacement, mother board flex replacement, when I start the phone I have nothing on the screen running only a red and green light on the top of the phone. I have disconnected the battery and load again but still the same. I tried power and volume down or up but still the same problem. I try with other screen but the problem is still there. Some people can help me in the diag and solution to resove ?