Re: Power button not responding
"Put your phone in rice" is the best way to ensure that it's going to die soon. It's probably too late now, but read
Wet Phone. (I've saved hundreds of wet phones over the years, including where "wet" meant "an unflushed toilet" - which is why I always had elbow-length industrial gloves in the shop.)
The reason the power button isn't working is most likely that the switch it presses got damaged by some of the contaminants in the water, and has to be replaced. (Pure water doesn't damage phones - it doesn't conduct electricity. It's the minerals, dirt, salt and other stuff that does the damage.)
Once a repair shop opens the phone, they'll probably tell you that so much has to be replaced (basically everything but the case and frame) that it's cheaper to buy a new phone. Copy off ALL data now, while you can.