I have been breaking things just to learn how to fix them, along with fabricating what I can't find, I have 11 trades under my belt. And use them almost everyday. when I have time I am happy to share what I know.
Once I got the back off I spotted my issue, This was a tough phone. 5 years of service in the marine industry. I spotted corrosion as I was unplugging. so I continued the battery had so much adhesive , you know the rest.
digitize r! It had drowned at least four times, was still working but had to be on the charger unless it was in safe mode. So good luck !
There are more symptoms for others to decide . I like this place reminds me as as a kid in the sixties, lol
I’m a boat service tech, my S6 has had several baths, if im not close to my house I wrap it a towel with a knot and swing it around mh head several times, pull the sims card set it in the sun with card opening up. close to house smae thing with but i have a block of soft foam i cut a slot in. wrap in towel put it in the washing dry on the longest spin cycle. after that i use a hair dryer no heat gun few minutes put charger on it as it warms the moisture expels as steam. put in front of a fan walk away. hour or so put card in it . off and running again. it’s 2015 model.