How can I troubleshoot a backlight problem (dim screen)?

Several months ago, my G Watch unfortunately went for a little swim and got water damage. I was able to remove the back and let it air dry for a couple days, after which the device seemed to work fine. The only noticeable issues I've had is a bit shorter battery life (but still enough to make it through a day) and a pretty dim screen. It is this second problem that I would love to fix.

I believe the issue has something to do with the backlight, but I have almost no knowledge of how that works or how I would go about troubleshooting/fixing it. The screen seems to have its full range of color, and the appearance of water under the screen disappeared a few days after I got it back up and running. The dimness varies from practically off to occasional full brightness (these moments are rare and usually fleeting). While dim, none of the software brightness controls have any effect, including the brightening of the screen when leaving ambient mode. I haven't been able to pinpoint anything that causes it to suddenly become bright for a while, but it has happened. For a while it would stay bright until I brought the watch out of ambient mode (by taking it off the charger, tapping the screen, or raising it as if to look at it), at which point it would immediately go dim again - a behavior I found particularly perplexing. However, I haven't seen this happen for a while. The most recent bright moment I had was after running around for a while (which may be a coincidence), and that time it actually started working as it was supposed to. Sadly, my excitement was short lived, as the screen went dim again the next day. I want to say the screen also stayed bright for a while after a cold day, but my memory is a bit foggier on that instance. It might have been a dream. :p I may be forgetting some details, but I'd be happy to answer questions that might help you pinpoint a cause for my problem.

TL;DR: My screen is dim after some water damage, and I would love some tips on troubleshooting and hopefully fixing the issue.