I don't have the most experience with that, but if I had that console in front of me, I would pop off the top screen lens with a suction cup and try and clean the lens and the LCD display with some IPA so see if anything changes.
Hopefully, those blotches are just the result of some overzealous cleaning from the previous owner and some fluid got between the lens and screen.
Worst case is it got into the LCD display and those blotches are on the light diffusion layers. Also not an impossible fix, but not one I tried with any sort of success. That requires prying apart the LCD with some force without damaging it.