Water damage; buttons switched functions

This one is strange...

Recently my G2 got in a bit of water.

While it still works perfectly, strangely enough, the functions of the buttons switched or something.

For example, when clicking the volume up button the volume does not only go up but down as well, so you can't really control the volume. The same with the volume down button.

The power on/off button keeps it function but also lowers the volume.

So what exactly happened beneath the hood?

I also want to eventually open the back, so I'd appreciate if you told me what to look for and how to fix it.

Thanks in advance :)