Where has the water damaged my S5

[AC Question]

I dropped my S5 in a flushing toilet 2 weeks ago and the screen is half dead. There's about 1cm of light on the lcd but most of it is black. Everything responds on the phone, home button, touch, etc. And there is nothing on my water damage indicators.

I'm looking at replacing the digitizer and lcd.. But am wondering if there's something else that caused the screen to die, since the water didn't reach the battery but must have gotten somewhere to kill the screen.
Is it possible the motherboard or lcd ribbon connection is damaged? Or am I completely off track and it's just the lcd?
It's strange that everything else works after being dunked and the lcd is the only thing that failed. I want to be sure it's just the lcd before buying replacement parts.

 

[Rukbat]

Everything metallic inside the case is damaged by now. Fixing it is going to cost a lot more than replacing the phone, unless you find someeone who gives his labor for free - then it'll only cost a little more to fix it. (See Oh, no! My Phone got Wet!.)