Amazingly, the burned-in line of the former desktop image has completely disappeared!
Once I realized that a thin white jagged line across the bottom of the screen was not a scratch as it seemed to get longer and spread out, I realized that it followed the lines of the image I used as a desktop. First thing to do obviously is to change that desktop image, suspecting burn-in. I kept the background dark so I could keep track of the line (okay, so I used purple, so what!) and for a few days it seemed again to blur and spread, but get lighter (or darker and less visible against the dark background). This morning, it’s completely gone.
So I suppose that burn-in, if caught in time, can reverse itself.
The Lost Children: A Charity Anthology