Why Rice Is Not Your Friend
The rice will absorb the water from the PCB (Printed Circuit Board) and will transfer the the moisture it to the surrounding air, but it will not absorb the minerals found in liquids such as water, and it’s these minerals that cause the damage and oxidisation not the water. When PCBs are manufactured they get washed in deionized water to remove any excess flux. Once washed the boards are then gently heated in an oven to dry, the trick is the use of distilled water as it’s free from corrosive minerals, unlike what comes out of the tap.
If you do try to use rice the oxidisation process starts almost immediately, sometimes taking as little as 12 hours to completely eat away at the components and PCB pads. Phones that have been wet and passed the 72 hours since drying time are usually very hard if not beyond the point of being recoverable. We have seen a lot of recommendations online to use this trick, although they mean well it is quite possibly the worst thing you can do apart from turning it on whilst still wet.