Vertical lines iPhone 7 after assembly

Where are you getting your assemblies from? Have you tried different suppliers?

There are a few things to take into account when fixing an iPhone 7.

1. Make sure you are grounded when working on them. Static build up can cause lines, but the lines shown in the picture look like lcd damage lines. Usually, lines caused by static are white.

2. When you are installing the small parts are you being extra careful with the lcd cables? When the cables are plugged into the mainboard you need them to curve into side of the iPhone back housing before you fully install the screen. This is where a lot of people will accidentally bend and pinch the cables. Im assuming this may be where the issue is coming from.

3. The last suggestion is to remove the small parts and test it again. If it works fine, you may have a problem with grounding of some sort. Depending on the manufacturer of your repair parts, look for any exposed copper lines where the original has none and cover them with kapton tape.