I don't have another one and it's perfectly black in the middle. I can't see any screen except on the outside. I already put it in boiled water and it didn't do anything.
try and scrape it or.... buy a new one. you can go to a headshop and get like a million screens for ten bucks.
get a pair of pliars or something to hold the screen with and burn the shit out of it, then scratch it
Buy some new ones man. They are quite literally the cheapest smoking accessory you can buy. But for now you can just put a bigger nug in the bottom of the bowl until you can get pack of screens.
This, just don't touch the screen with your fingers until it cools down, don't ask how I know, lol, it works great.