Contrary to what many think, electronic equipmant doesn't mind water too much, provided there's none of it around when the power is on!
This is what I'd do if it were mine, but it's not advice, it's an "at your own risk" suggestion:
Wash off all the dirt you can see with clean, preferably distilled, water. Pay attention to any nooks and crannies. A squeezy or spray bottle and a soft brush might help.
Pat it dry as far as you can, then put it somewhere warm (eg the airing cupboard) to dry out for at least 24 hours.
Then connect it up, say a short prayer and switch it on.