I have a problem with my Samsung Galaxy S II.

Firstly, a couple of days ago I accidently fell into the river with the phone in my pocket. Big mistake on my part I know. I immediatly took the battery out and dryed it. However I did power it up only about 10 mins after (now I know otherwise). However, when I powered it up everything was fine, for a couple of hours. Skip ahead about 3 hours later I notice some issues with the phone, accelerometer doing weird things and most importantly the phone thought it was plugged into USB. I decided to turn the phone off, then attempted to turn it back on, however nothing happened. Once I got home, about 6 hours after initial "dunking", I put it in a sealed container of rice for about 30 hours. When I finally powered it on after that, it seemed ok.

However, I am now getting messages saying that "MTP connected" which means USB connected. Also, when ever I power down my phone I get this message: http://goo.gl/yp9Ha .

To power the phone on I need to get into the hard reset menu and reboot the phone. This is the phone in normal state (note there is no usb connected: http://goo.gl/p0xGy).

Here is the USB port: http://goo.gl/9a58F

So, I think the issue is with the usb port, possibly a bit of corrosion. I am going to try and get some rubbing alcohol and clean it. I bought the phone from DSE, but I think I will take it into a Voda store (Newmarket) to get them to give me some options. 

So is there anyone who could maybe give me some assistance before I have to give the experts my money?

I know I made some mistake, but I can't afford to buy another one, $1000 is a lot of money for a 16 y/o!