No backlight and bad battery after water spill

You need to dissasemble your macbook and use 99% alchol and a tooth brush (perferably new) and scrub everything dont be afraid to pour the alchol on the board just don soak it ! once youve applied it scrub scrub scrub then i would let it dry for 24 hrs. then if the backlight is still messed up you would need a new back light fuse put on bascially . and if you need a fuse your gonna have to get a new one off ebay or something for your specific model then solder it back on to the board but i would say before you do any of this send it to a professional most rates are $325 and they have actual machines instead of toothbrushes and such! BUT ITS POSSIBLE! You basically wanna get all corrosion off the board! Then Start diagnosing from there and start replacing the parts to make it work again!