Water Damaged iPhone Questions?

Two days ago I was cleaning my pool when I accidentally fell in for about 5 seconds. I got out and laughed about it, until about three minutes later I realized my phone was in my pocket, right then panic set in.

I had no idea what to do so I checked to see if the phone still worked by just hitting the home button, it did, but it looked like it was glitching and showing these small aligned squares in the middle of the screen (mind you the phone will still soaked when I did this). So the only thing I could think of doing was putting it in a bag of rice, while it was still on.. I'm a genius, I know. Once the panic settled down a few minutes later I then realize I should turn the phone off, when I went to do that there was no response, and I foolishly tried powering it several times. After doing some research I found rice was practically useless and just replaced half the rice with some silica gel packs to let dry. Once the camera looked like all the moister was gone I tried connecting my iPhone to iTunes, but once again, no response whatsoever (probably shouldn't have acted so fast considering it could still be wet inside).

I lost patience and hope at this point so I decided to take matters to the next level. I have some experience with repairs and builds so I'm fairly confident in deconstructing my iPhone, which would be a first. So far I've taken apart the battery, and tested it with my multi-meter, and came to the conclusion that the battery is fried. I'm gonna head to a batteryplus and see if they have any iPhone batteries later today. Now that you've got an idea of what's happened, I'd like to ask a few questions. What all do you think could've happened here? The small boxes on my screen when I checked the phone after it was just in water could've been from what? I know the battery is forsure needed to be replaced, I'm wondering if anything else might need fixing because there was absolutely no response from iTunes? I tried several wall plugs and my computer while doing a hard reset for 30 seconds each time, as well as doing a hard reset and letting go of the power button while still holding the home button then connecting to iTunes.. still nothing. What could this indicate? Again, I'll be getting a new battery hopefully today so I can update you all on everything once that gets installed. Any help will be GREATLY appreciated, thank you for taking the time to read this, and hopefully we can get this phone working again :)

Edit: I also forgot to mention when I opened up the phone, the only corrosion I could see was at the bottom of the phone. Then again all I took off was the battery, everything else is in tact. So I cleaned up all I could see with a a q-tip soaked in 91% Isopropyl alcohol. All the stickers were red obviously, and I'm wondering now if I should check and try to remove any possible corrosion deeper inside the phone.

Update: I am using the guide @gigabit87898 linked and am cleaning out my logic board, so far before I clean it, there aren't many signs of corrosion at all, very little in fact. I will be cleaning this all with my 91% alcohol as well as getting a new battery at batteryplus hopefully later today. If this and the new battery doesn't work, what should I do? Invest in a new logic board? If it powers on but no screen display, invest in a new LCD screen? Thanks, again, all help is appreciated.

Update: After cleaning the logic board with the guide above, and installing a new battery, I still get no response from the phone. No response from iTunes either.. what do I do????????