First and for most Stop plugging it in keep it away from power and do not try and turn it on... these are your 1st steps if you can go without trying to turn it on and get it open as fast as possible set out a white towl and start dismantling it... First thing is get the batter disconnected soon as possible...
If you do this and get moisture cleaned out you will have a chance on bringing a drowned phone back to life.. but only if very quickly power gets removed and parts come out for drying. in just few hours you would not believe the corrosion that begins.
I still today use a phone that went in the swamp in my pocket was over my head so the darn thing for sure got soaked water was actually running out of it when I got out the water regardless I powered it down and held it strait up and down so water would drain as good as possible.and got it opened and cleaned and dry. that was a year ago still works today but ya gotta open it up and start drying ... and hope you have not been trying to plug it in at al cause if so there is little hope......what area are you located in?