Not charging after screen replacement

We replaced new Oled screen. But phone is not showing any charging sign neither turning on. When we inset charging cable and press power button to turn on, than only Google sign appears and disappear. There is no sign of charging also. It shows sometime red battery sign for a second when we press power button.

can you tell how we can fix it that it should start to charge normally and turn on?

once it was showing some software display as I have attached. But this display is no more.

Thanks