I've worked in electronics design & manufacturing all my life and all PC boards are washed in a washing machine, much like a dishwasher after assembly. The flux used in the soldering process is water-soluble. So, there is nothing on the boards that clean water can hurt as long as you don't power up anything till it's completely dry. There are likely other components that could be damaged, however, like motors, etc. If you can get the water out of everything (going to be hard to do without a full disassembly), chances are it will probably be OK. I don't know if the batteries are water sealed, or if they can be opened up, but that's one area where you need to check carefully. Good luck!