How do I fix my iPhone 4s after it has water damage?

katie, skip the rice. The "rice trick" is one big myth. Placing your phone in rice is equivalent to doing nothing. It does not prevent any kind of corrosion or fixes your phone. The best thing to do is to stop using the device, (remove the battery) and to totally disassemble it. Use these guides for that. Then clean it with +90% isopropyl alcohol. This will displace the water and stop corrosion. It it okay to submerge a board in isopropyl alcohol. Check this guide to show you how to do it. After that, air dry all the components. Do not forget to clean the connectors on the board as well as the cables. Then re-assemble with a new battery. This is not optional but a must to avoid failure later on. " Check your board for any missing or damaged component. Water damage is the toughest to trouble shoot and to repair. Hope this helps, good luck.