[DonRotolo]

Um, seriously: It is good that it was powered off.

Take everything out and wash it in clean water. Things like speakers and wires are trash (as are breakers), but PC Boards are usually OK since they get washed as part of the production process.

Disassemble the cases of each item, then wash and lightly scrub (use a soft bristle brush like a toothbrush) under water to remove any surface contaminants (like mud). Rinse in clean water, then rinse with 91% isopropyl alcohol and set it to dry. Blow the board with compressed air or a 'duster' if possible to get any trapped liquids from under components.

After it dries - at least overnight! - inspect the circuit carefully. If you don't see any corrosion or other issues, let it dry another few days (you can bake it at about 130 degrees Fahrenheit for 2 hours if there's no plastic), then reassemble it (you cleaned the casing, right?) and power it up.

In about 70% of such cases the device will power up and run fine. Conformally-coated boards like Jaguars and the PDB will have a high success rate.

Unrelated: This also works with phones, but few of us can disassemble the phone for this. Note that phones also have moisture-sensitive labels which turn color to show it was wet, thus voiding the warranty. If you can't disassemble the device, it is often trash, but rinse it thoroughly in distilled water then let it dry for a week or more; ideally sealer in a chamber (like a ziplock bag) with a desiccant (such as silica gel or, in a pinch, white rice).

Good luck, let us know if you did this and how it turns out.