The black or colored dots on the screen can be caused by damage on the screen. The damaged screen should be replaced with a new one.
If there is resin leakage on the screen surface, refer to How to Replace the LCD Screen and clean the resin.
If the leakage is inside the screen, replace the old LCD screen with a new one.
The phenomenon is that after the exposure test being conducted:
The issue can be caused by incorrect firmware. Download the latest version of the frimware and update it on your printer.
If the problem still appears after updating the firmware, re-plug the LCD screen ribbon cable.