Help Water damage - USB won't connect to PC.


Hi there,

My phone recently fell into a water bucket and I immediately pulled it out.
Not much damage was done to it except of one thing.
After I put it in a bag of rice like stated on the internet for overnight, and then plugged it in again to the charger, it seems like something was different.
Phone DOES charge, but nothing else happens.
It doesn't turn on screen and informs "charging", and doesn't have the "charge when phone is off" option anymore. Instead it would just turn the phone on.
Also, when connecting the phone to the computer nothing happens, it's just charging the phone! can't mount USB anymore :(
I took the phone to a lab which handles these cases. They replaced the USB port and cleaned all the corrosion. They said it's fixed now, and indeed the USB port is new.
But then after coming back home it's still the same.

I'm sick of being dependant on other people and would like to fix it myself.

Any clue which part of my phone was fried? Where can I get it?