Changed broken Display, now bootloop

I got an Kindle PW2 with broken display. I have another display and when I tried it, the Kindle is stuck in bootloop. It connects to PC and there‘s a device with no medium. When I put the pcb on the broken display, it boots straight into system. I tried another known working pcb on the spare display and it‘s also in bootloop. I can‘t figure why a display can cause this issue.