Why won't my galaxy s4 turn on?

Your first problem was using rice does nothing at all don't let people say it absorbs the moisture its a load of bs.

Phone needs washed out with ISO alcohol then tested

Upon dropping a phone in water.. it is important to take the battery out to let it dry out. Try a new battery, if that does not work then ISO alcohol with light scrubbing of motherboard may bring it back to life.

I'm embarrassed to know the origin of the rice story. A long time ago some dude translated a service manual from Japanese to English. Everything was kosher except he added "Take care when removing the cover so all the rice does not fall out." The Asian electronics rice thing is at best a racist joke and not very funny. How people believe this astounds me. Think about it. Rice absorbs water but only when you boil it for 14 minutes! Spread the word so people stop doing this and ruining good phones.

WET PHONE

Do NOT try to turn it on!

Step 1) Remove battery if possible.

Remember DON'T try to turn the phone on!!!

Step 2) Take phone apart and remove battery anyway!

Step 3) Dunk phone totally into 99% Isopropyl Alcohol.

If you offer to do wet repairs on phones use ONLY 99% Isopropyl Alcohol. The stuff at the drug store has too much water in it. If you use 99% you need to rinse it really well. And that means totally covered. You can't splash Alcohol on and expect it to work. I believe the phone should be broken down so you can get in there with some compressed air and blow any loose "crust" out or water that may have collected under the components.

Search for SWAN 99% Isopropyl Alcohol

Good Luck! Jay at refurbatron.com