iPhone 5s bootloop with damage after DIY repair

Hello kind people of iFixit.

I have recently tried to replace the battery on my iPhone 5s, but I sliced trough the ribbon cable for the power button while prying the battery out. While I waited for those new parts to arrive I tested the iPhone, because one of the screw standoffs on the motherboard had gone missing and I was afraid I broke it. No long screw type damage, luckily. The phone booted and worked absolutely fine. Then I replaced the power ribbon and put the phone back together; bootloop. Something I notice when it reboots is that there is a small horzontal line over the screen for a split second.

I’ve tried reseating all cables, the board and all other components and trying it without the new ribbon but same thing. I have also tried restoring the iPhone. It goes into DFU mode fine, but after initiating the restore and shortly after the progress bar appears on screen it reboots with iTunes error 9. After closer inspection I noticed that a very small component next to the battery connector had gone missing. Could this be the reason why? https://imgur.com/a/a9pDX