This app was mentioned in 10 comments, with an average of 0.40 upvotes
Can't help you with your problem but if that burn-in is annoying you I'd consider downloading something like Pixel Fixer and running it overnight, although yours may be too severe.
Since your phone has an IPS LCD display, the image will fade eventually. Leaving your phone screen off or on a pure white screen can help. Running this app might help.
I think its by using apps like this one https://play.google.com/store/apps/details?id=com.aiuspaktyn.pixelfixer
Try 30 minutes or so of this https://play.google.com/store/apps/details?id=com.aiuspaktyn.pixelfixer Can't hurt and may save you an RMA
I ran this app for 6-7 hours last night and it seemed to fix it but YMMV
https://play.google.com/store/apps/details?id=com.aiuspaktyn.pixelfixer
It might not be permanently burned. There is an app you ought to try..
https://play.google.com/store/apps/details?id=com.aiuspaktyn.pixelfixer
Also just to note I had this happen on a Gear S3, and it went away after a few days of normal use.
https://play.google.com/store/apps/details?id=com.aiuspaktyn.pixelfixer
Light burn in can be fixed with this app