LCD screen not working after replacement.

Theory:

If you put the screws in the wrong order, is it possible for the screen to not work?

Actual problem:

At the moment, I have a perfectly working screen. However, the moment I put the back lid on and screw everything in place, the entire LCD doesn’t come on anymore.

Question:

How can this be fixed?

NOTE:

The phone had water damage but the motherboard has also been replaced and the phone was treated for water damage as well.

Step already undertaken:

1. I have tested the screen by replacing all parts by (original) parts from a working LG V10. and the screen worked perfectly.

2. I have assembled the entire phone except for the side railing, the screws and the back cover. Without these three parts, the LCD works perfectly as well.

3. All current parts have also been tested by putting these to work in an already working phone. Every part works fine.