Downloading please do not turn off target

So i dropped my phone in water. I put it in rice and ordered a new battery. My phone will turn back on but its stuck on this baby blur screen tgat says "downloading please do not turn off target" I have a Samsung galaxy express prime. Thanks

Welcome to Android Central! Download Mode typically requires that you power on by pressing Power and Vol Down (and possibly also Home). It may be that the water damage has caused your Vol Down button to register as always pressed down. Water damage can be widespread and unpredictable, so even if you got your Volume button replaced, that's no guarantee that the phone will work normally afterwards. Sorry!