Screen blur after heating phone

If the screen became blurry right after the phone got hot, I’d let it cool completely first and see if the image returns to normal.

If it clears up once the phone is cool, the display may just be reacting to the heat. If it stays blurry after cooling, the LCD/digitizer may have been damaged by the heat or the display layers/adhesive may have been affected.

I’d power it off, let it cool naturally for an hour or so, and avoid using a fridge/freezer to cool it down. If it’s still blurry afterward, I’d reseat the display connector and inspect the flex cable for damage. If that doesn’t change anything, the screen assembly is probably the part that needs replacing.