iPhone 5c black screen but is on!

Hey

I just got a used IPhone 5c From a friend that was having trouble with the screen being completely black but the phone was still on,that dropped the phone in the bath a couple of mouth ago but it worked fine and has had the screen replaced before,so when I got the phone I bought a new screen for it and it just come in today so before I moved everything you need from the old screen I plugged in the new screen to make sure it worked,the screen is still black with no lights at all but the phone still turns on. If anyone know what else could be wrong I would really like to know.