So i had a Panasonic Lumix GH4 submerge for a split second under seawater. It died. The battery had some of that blue-ish corrosive battery acid stuff on the metal connectors. After 24 hours in rice, the camera wouldn't budge. Two days later the function lights started weakly blinking when I'd insert the battery. Then when I just checked again, the whole thing came on, working fine. I pulled the battery and put it back in rice to be safe. So going forward, if it miraculously does work after fully drying obviously the salt is going to be corroding it. Should I make sure there is no power and put it in fresh water and let it dry for a week again?