iPhone 4 warm : How to find a shortcut in the motherboard.

Hello,

I have an iPhone 4 who was in contact with anti mosquito oil.

Unfortunately my wife continued to use it directly after the drama.

The only consequence was a died lcd screen (every colors were lost but we could still distinguish the shapes, menu, etc.)

So I decided to change the lcd screen. But 2 days before changing it, it was impossible to turn on the phone and I had died battery symptoms. (phone never charging with always the red battery draw on the screen).

Anyway, I changed successfully the lcd screen and the color came back.

But the problem of charging was still present.

So, I after having tested the battery with a voltmeter (around 2V instead of 3.7V) and the phone with another battery. I bought and installed a new one and the iPhone turns on but now here are my problems:

• When I plug the battery the iPhone becomes really hot (you can't take it in your hands after 5 minutes) and even turned off!
• When I turn it on, the battery is discharging really fast (2%/minute)

I didn't let the battery plugged too much time (I guess it will died) and so I suppose there is a short cut somewhere in the mother board.

Do you know how I can find the gulty chip or component and if I can fix it? For information, the problem comes from the lower part of the motherboard and not the upper one (A4 ship stay cold)

Thanks in advance for your help.