My iPhone 7 screen turned black, how can I fix it?

Last weekend I dropped my phone in water and quickly dried it off, took out the sim card and put it back and left it to charge. A couple hours later it was back to normal. Today, it was working just fine until randomly the screen went blank and the buttons didn't work, as if it died. However, it was plugged in the charger and was working minutes before. So just now I took out the sim card again and put it back and have tried force restarting it over and over... I don't know what else to do.