What to do if water spilled on it and it got inside

Been here before. First, shut the machine off and remove it from power immediately. Then you are going to follow this guide here to remove all the major components. Unfortunately, there is no guide for your model as of yet, so the one I linked is the most recent one before that. Once you have removed the logic board, you are going to want to wipe it, as well as the other components, down completely with 70%+ Isopropyl alcohol (rubbing alcohol). Let it dry for 24-48 hours in front of a fan, and then once you are sure it is completely dry, you can begin to reassemble your machine. You can also take this time to clean out your fan if it has dust built up in it. For this task I recommend this toolkit: [verlinktes Produkt fehlt oder ist deaktiviert: IF145-047] , this mat:Magnetic Project Mat , and you will also need this driver: P5 Pentalobe Screwdriver Retina MacBook Pro and Air. The kit will definitely come in handy in the future, but if you want the absolute bare minimum, you will need: this, this, and this. Hope this helps.