Chosen Solution

The screen works only at a very acute angle, at 90 degrees or normal upright it’s just black.

This is a sign of a loose connection in the monitor. I had this issue with my old laptop, it kept flickering then eventually turn white unless at a certain angle. A little knock would change it white. when it got repaired, it was because the connectors in the monitor was loose. So thats your best bet. Please et me know if ive helped, Ryan