Mystery 'watermark' in the background (all the time!)

[loganrunn]

I purchased a great condition used Galaxy S7 Edge. It appears to have a permanent watermark in the background of the phone - I have tried 2 hard factory resets, and to no avail - still there.

The watermark shows everywhere - taking photos, looking over photos, mainscreen, text messaging... everywhere. The watermark says the following :

Galaxy S7 Edge B2C
video/0_Hero2_attractor.mp4

This mysterious watermark is a faint red color and also has what seems to be a 'burn' of red behind the letters. How can I hack into the phone and perhaps replace this with the factory solid white background?

I have a photo to show, but this forum won't allow me to upload - can anyone help with this issue? Thanking you in advance.

 

[SpookDroid]

If you take a screenshot and then view it on a different device, does the 'watermark' show, too? Or is it just on your screen? Sounds like it could be 'burn in' on the screen, which would cause the image to show on top of everything all the time.