Here this post explains why vertical lines on iPhone after screen replacement: http://www.hcqs.us/blog/vertical-lines-on-iphone-after-screen-replacement/

There are 3 possible reasons for the problem: 1. The touch screen could be faulty. Screen replacements are manufactured by third party companies and sometimes their integrity could not be meeting the standards. For instance, you can get a screen replacement part being manufactured in India when the phone’s company is located, say, in the US. 2. The flex cable is not rightly in contact with the connector. This implies that the signals from the screen won’t be conveyed to the phone. 3. The same flex cable could have been damaged during the reassembly process. This gives people a lot of headache since the torn part could not be visible sometimes.

Hope this guide will help you: http://www.hcqs.us/blog/tell-copy-parts-from-oem/

There are 5 possible reasons for this problem: 1. Power Distribution Issue 2. The Dead Battery Issue 3. The Damage Board Issue 4. Assembly Issue 5. Flat Cable Connection For more detailed info please check this guide: What to do when iPhone Won’t Turn On After Screen Replacement

Under the iPhone’s battery plate, there is a silver connector which has to be unscrewed prior to disassembling the iPhone. If this connector has not been replaced properly, the iPhone will fail to connect to a mobile network. Check the post below to deal with the problem: How to Fix iPhone No Service after Screen Replacement

If you have just replaced your screen and got the problem you can check this guide: How to Fix Error 14 after iPhone Screen Replacement

Usually there are 5 possible reasons for the problem: 1. Power Distribution Issue 2. The Dead Battery Issue 3. The Damage Board Issue 4. Assembly Issue 5. Problem with Flat Cable Connection You can find more details here: What to Do When iPhone Won't Turn on after Screen Replacement

There are several reasons for this problem for example pry damage, a malfunctioning lightning port and so on. You should troubleshot the problem by following this guide: How to Fix iPhone Home Button Not Working after Battery Replacement

During the replacement of the iPhone’s screen, the four screws holding the plate over the screen connectors are replaced. These screws are not all of equal length. If you fail to note which screw goes into which hole and try to insert a long screw in a hole meant for a shorter screw, it can damage the logic board of the device. This will cause an iPhone boot loop and a blue screen. Performing a DFU restore will not resolve this issue, it will result in an error. You can refer to this guide: How to Fix iPhone 6 Boot Loop after Screen Replacement

Here is a guide for this problem: How to Fix iPhone 6 Ghost Touch after LCD Replacement