Touchscreen and lock button issue after battery replacement

iPad mini 4 LTE Akku austauschen
After following this guide on replacing the battery in my iPad mini 4. The ipad has a few issues. There is a small portion of the screen about 5-6 cm from the top that no longer registers touch input. The lock button cannot be used to lock the iPad although it can still be used to shut it down. I heard the lock button issue can be due to the smart cover setting but the "iPad case Lock/unlock" setting is missing from the settings.
I have experience with replacing batteries and Screens in iPhones and have never damaged everything so I doubt that the display ribbon cable was damaged during the battery relacement although that could be the case