Data not being displayed on screen; LED backlight fully functional

I spilled about a half cup of water on my keyboard and screen, and didn't get it shut down before some artifacts started showing up on the screen, like something was shorting out. I let it dry out and then started it back up, and from that point onward I've had to use an external monitor, because all the MBP screen shows is a backlit grayish hue with some vertical columns and some greenish yellow vertical lines. Everything works fine on the external monitor, so I though maybe the data display cable (LVDS) shorted out. Bought and installed a new one via ifixit, to no avail. Replacing the LVDS cable changed nothing, unfortunately.

I talked to a tech in the Bay area who said it was probably a short on the logic board, which would make sense given that the new (i.e., used but tested ifixit) data display cable didn't fix the problem. Yet, I inspected with a big magnifying glass the area around where the data display cable connects to the logic board and didn't see any shorts (can they be seen?), and further, I can't figure out how any water could have gotten to that particular place (it's a ways down the logic board, away from the back entry point and not directly under the fine open line under the bottom of the keyboard).

If water shorted out some other place on the logic board, wouldn't it have affected something other than the display of data on the native screen? Again, everything else has been running fine because data is being displayed perfectly on my external. Any speculations as to where the short is? I'm guessing that replacing the logic board will fix the problem, but I'm curious about what exactly happened. I couldn't find much of anything via google on this particular problem.

Thanks much,

Wes