iPhone 11 pro max display replaced lags?

I replaced my phone's display yesterday because it was cracked. I reattached all the connectors and screwed them back in place. Now I swipe up in a WhatsApp chat and suddenly the app closes. I call the person or the chat closes. I swipe left on the home screen at the bottom of the display and random apps, etc., open.

Normally, you can tap the display once and it turns on. This only works occasionally, about every 10 attempts.

I bought the display from Kaputt.de because I thought the site had a good reputation. Apparently, however, it doesn't live up to its reputation.