I usually agree to this but @Prinzabu actually did it correctly. There was no water used on the electronics but Isopropanol. The water and soap were for the removed panel and the removed keycaps.
Isopropanol is usually sold as Contact Cleaner, however, Contact Cleaner is not always the same thing all around the world and may some times(but very rarely) refer to products containing oils that will leave a “corrosion protecting” residue used for connectors in moist environments. You absolutely don’t want this on your circuit board. Instead just buy Isopropanol if you are uncertain what it contains.
Make sure to not let Isopropanol inside the encoders or potentiometers as it will cause the grease inside to wash away. For encoders and potentiometer internals use DeOxit with Fader Lube.
/Olle