Recent apps hardware button stopped working

Yesterday when I took a shower, I think my phone may have gotten splashed with a little water.

After a bit of use today, I noticed the right hardware button wasn't responding to being touched. The button worked fine last night after my shower, so I hoped it was just a software problem. I rebooted and cleared the system cache in recovery, but no dice. I also tested the button in the *#808# menu, and it failed to register input. Interestingly, the button still lights up when the home or back button is pressed.

Everything else on my phone works normally. Does it seem conclusive to you guys that water damage is the cause?

If so, would you recommend attempting the repair? I'm pretty handy (work on my car, built a PC, etc) but I've never taken a phone apart. I watched the video, and it didn't look too tricky, but I won't attempt it if there's a good chance that I could easily damage other parts of my phone when attempting the repair.