So the situation was: black screen on normal startup, but safe mode worked fine.
I originally thought something was wrong with the startup process itself, perhaps BitLocker had gotten corrupted, but a startup repair eventually ruled that out.
Seems like it was the graphic cards display adapter that was acting funny and the fix was surprisingly easy:
Simply uninstall the display adapter driver via Device Manager, reboot and it should be fixed.
Windows 7 reinstalled the malfunctioning driver and it fixed the problem right away.
I still recommend to be cautious when uninstalling drivers though, don’t want the screen to be permanently black would we..