Was the water source of the splash, fresh or saltwater? If salt, then a non-weather sealed body is in trouble because the only treatment that works is immediate and radical. It has to be flushed with distilled water and that has to be done immediately (within a few minutes).
But assuming it was fresh water, the prognosis is good. Keep the battery out for now and put the camera in a fairly warm environment where the humidity is low. I restore some pretty old vintage electronics gear and sometimes it requires a high impact washing to give it any chance of reliable operation. When I have to do that, it gets a final rinse with distilled water followed by proper rapid drying. Fortunately your camera doesn't require such treatment.
In front of a dehumidifier is a good way to provide rapid drying as long as it isn't located in an area where the humidity remains too high. If you have a dehumidifier in your basement, temporarily move it into a ground floor bedroom and run it there with your camera in the output air stream for a day or so. Do NOT put the pair in a closet or the dehumidifier will rapidly overheat.
Or if you have access to desiccant packs, using those in a sealed bag with the camera will rapidly remove the moisture. I have a bunch of reusable large mil spec packs that change color when saturated, they get baked for reuse. When traveling with cameras, I also have sealed bags of desiccant with me. Do NOT use rice or other "youtube" food methods. These may be fine for cell phones but the dust and potential outgassing that these generate when they absorb moisture is not good for cameras.
This is also another good reason for keeping the body of the camera clean because the salt and oil from your skin being wicked into controls is what causes damage by turning fairly low mineral fresh water into salty water.
And shame on Canon for not providing better weather resistance in all but the very cheapest bodies. Making something with external controls waterproof for submersion is very expensive, making them robust against splash isn't and it is reasonable to expect it will be exposed to moisture sources. Standing in the surf and having a surprise wave break over you should reasonably be expected to cause damage, getting splashed by a breaking wave shouldn't. This problem is made worse with designs that create more heat in the camera body because when hit by water it will be rapidly cooled causing air pressure inside to drop which will be relieved by bringing air (and moisture) in through the point(s) of least resistance and that is often the shafts around the controls.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
