Exposure Test ?

Hello !

A friend gave me an old Elegoo Mars 1, which printed good for the firsts prints. But I started to see defect on the center of the build plate. So I did an exposure test and had those results.

Not sure of what I'm seeing. As there is a large black spot on the screen I guess it is burned, but on that image is the same as the one on the touche screen, that makes me doubt.

Any advice ?

https://preview.redd.it/t9ehvc8flgke1.jpg?width=4032&format=pjpg&auto=webp&s=a027529052c1f7ae37541b99b2a3ac3eb94e459e

https://preview.redd.it/nzkbi59flgke1.jpg?width=4032&format=pjpg&auto=webp&s=8754b7ce291adf28083027371542867dd8bf9630

https://preview.redd.it/lvj9oe8flgke1.jpg?width=3024&format=pjpg&auto=webp&s=4ce12d67a8a5327b55d17671972ae77bd0ceb9eb