What's causing the problem with my gradually dying display/backlight?

2 or 3 years ago I knocked a glass of water over and it got all over my open macbook pro. I immediately turned it off and placed it upside down on my table. I tried drying it off with a blow dryer and let it sit for several days. Upon powering it back on the display worked, but would start flashing on and off at random. I took it apart and cleaned the logic board, which looked pretty good to me, but I'm no expert (obviously). Along with the randomly flashing on and off, the display sometimes had alternating light and slightly dark spots across the bottom of the screen, and sometimes would not come on at all. I tried connecting to an external monitor and had no issues at all. When shining a light at the display you can still see what I have open, but there's no backlight. It seemed like the display would work fine for months and then suddenly not work. Those occurrences have gradually become more often and now it's almost all the time either darker than I have set the brightness and won't change when trying to adjust (sometimes it will adjust) or not working at all. I have noticed that plugging the charging cord in seems to wake the display up (or the backlight). Sometimes I'll plug it in and it will look normal and then immediately go back off, and if I unplug and then plug the cord back in it'll come back on (and then sometimes go right back off again). As of the last couple days I haven't been able to get the display/backlight to work at all. Will someone help me figure out what exactly I need to fix/replace? I'd really appreciate it! I don't know if it's the display, the battery, or the logic board or something else altogether! Thanks in advance for any help!