Screen shuts off after replacement
I have a weird problem that hopefully somebody can help me with. I changed the screen on a MacBook Air 2019 and after the screen replacement it now boots directly to a black screen (boot sequence is working/apple logo + progressbar is showing). If I shut the lid and opens it again, the image appears for 5 seconds before it turns black again. There's a tiny blue dot in the uppermost left corner when the image disappear. Backlight remains on and adjusting it works; but the image is gone.
External monitors work fine. Recovery/safe mode works fine. I've reseated connectors, but everything looks fine. Cleared NVRAM/SMC, reinstalled macOS.
The previous monitor showed an image constantly but had purple lines and incorrect coloring.
Thanks for your help.