black screen and green vertical lines after lcd replacement

I have seen this a couple times in our shop. So far my co-worker and I have figured out that it is some kind of short on the board, After market screens will show the greenish weird vertical lines. Choice screens show nothing, however the backlight is lit up. The 2 phones we have encountered with this problem were iPhone 6. Both customers used car chargers religiously. The black out issue only became a problem when the battery was disconnected, and reconnected after a screen replacement. We have tested fuses and found none faulty. iTunes recognizes the phone, screen is still black. Besides the 2 we have in the shop, I have encounter at least 3 more with this issue. Those 3 were fixed using Rec Boot, a tool to place a phone in and out of recovery mode. I put those phones into recovery mode, and when I kicked them out of recovery that fixed them and the screen came back to life. The other 2 we are still working on to find out answers. Have not replaced the backlight filter fuse yet. We will see...