Son peed on Samsung Galaxy 4 Note phone?

My son fell asleep with Samsung Galaxy Note 4 underneath him and peed on it last night. He only told me it was displaying android screen downloading do not turn off. Please keep in mind when he told me about phone acting up he didn't mention what might be wrong with it so I googled what to do and came up with pressing power key and volume down button. So I did that phone turned on like it was suppose to and then we noticed it wasn't responding to touch on screen. The battery was dead so I decided to let it charge and then see what could be wrong. Hours went by and I checked it, still not responding to touch. I googled again and took off back to take out battery and SIM card that is when I noticed what I thought was water but then my son admitted it was pee. So I googled what to do, phone is now in rice and I'm hesitant to turn it back on. Any suggestions of what else I need to do before powering it back on?

I know nothing about phones hence googling everything so I do not feel comfortable removing screws to get to water damage indicator.

Read more: Son peed on Samsung Galaxy 4 Note phone?