darkened screen after water damage

Hi. You should take the phone to a repair center asap (Today) and get it treated for water damage. Do not turn on the phone. The quicker you do this the more likely you are to save the phone. If you have phone insurance, then now would be a good time to use it. If you wait too long, then the phone may end up beyond repair. Don't be tempted to use the mythical "Bag of rice" method as this doesn't remove the harmful deposits from the electronics inside the phone. Trying to power on the phone will cause more deposits to build up from the liquid and hence more damage. Good luck.