I've cleaned up a number of Amateur Radio HT's over the years that had soda or whatever dumped on them...
Water is your friend, but you want to try hard not to get it inside. If for no other reason in that you don't want to push the "offending substance" further in.
Electricity is not your friend. Remove the battery. Careful though, sometimes the seal around the battery is part of the "waterproof-ness".
Isopropyl Alchohol can also be used to clean things up but you want pure stuff... not nail polish remover (acetone plus other stuff) or anything like that. Walgreens used to sell the relatively pure stuff. 99%. Nowadays you have to hunt around a bit for that. Stay away from "Rubbing" Alcohol... it's typically a mix of alcohol, acetone, and water. And you're trying to get rid of water... but I've successfully used "91%" in a pinch cleaning up gear.
The purer you can get the stuff, the better... if it weren't for the display and some capacitors that aren't sealed well, and possible reactions with some types of plastics/rubber buttons, you could just drop a device in 99% isopropyl bath and get the water out.
Here's how I usually clean up a radio...
- Start by just getting bulk off with rags/towels/paper towels. Get out some Q-Tips and get it out of nooks and crannies, etc. The HARD part is keyboards... you're not going to get everything out of those buttons without disassembly, but you can get most of it.
- Remove battery when practical.
- Warm water carefully trying to keep most of it on the outside of the radio... look at the direction of mic/speaker slot openings, etc... try not to squirt water THROUGH them, but more ACROSS them... don't dunk the whole radio in water, of course... wet rags that aren't "drippy" often work well at this stage.
- Once you have the radio "clean" ... now you may want to consider disassembly... especially if "stuff" got inside. Careful removal of outer cover and looking around for signs of where the "stuff" got in, and Q-Tips, small soft absorbent rags, and very little water, or the above-mentioned alcohol work well at this stage.
- If there's signs that the "stuff" got on the electronics inside, you want to get it off. You might want to discuss with an electronics tech before pouring anything on the circuit board however.
- Once you think you got it all out of the nooks, crannies, outside, inside... wherever... RESIST the temptation to power the radio back up. You want it dry, dry, dry before you put the battery back on. (Ask me how I know... ha...)
- Some folks use the "bag of rice" trick... as long as there aren't a bunch of little nooks and crannies to catch the rice in... you can put an electronic device inside a bag of dry rice and seal up the baggie and the rice will "draw" moisture. There's also of course, those commercially made silica gel bags you find in most electronics purchased from Asia these days, that also do a great job of sucking up moisture. Leave the radio in the baggie for a day or so. You want it as dry as possible BEFORE putting it in the baggie, anyway... but the baggie trick can help, especially in humid climates.
(Here in Colorado, we're so dry all the time, I just leave the battery off the radio, maybe even the case off, and set it aside on the workbench for a few hours... a full day and it'll be bone-dry.)
- Some folks use canned air or even a rate-limited attachment to a shop air compressor to remove the moisture... just have to be really careful with it... the speed of the air at the nozzle is high enough I've seen components ripped off of circuit boards. Also I've seen compressed air more than once shove the water into the cover of the LCD screen. LCD's and water don't get along, and looking at water spots on the inside of the LCD cover for the rest of the life of the radio... isn't nice. So think about where you're blowing the water if you go that route.
There's some options... I've both fixed stuff, and "not fixed stuff" (or they were already fried and no amount of clean-up was going to fix them)... with the above.
Coke is EVIL on radios. At least you're just dealing with soap...