Just had this happen today. Dropped from the sky like a rock (one of the stock motors lost a retaining clip and spacer and it shorted the ESC). Fell right into a pond. It took me about 10 minutes to find it, and pull it out. The yellow status light was still blinking despite being under 1' of water and on its back.
I immediately yanked the battery. Took it inside, disassembled everything, and using a needle (ball) inflator on my air compressor, proceed to blow every component dry. You have to carefully remove the padded foam that covers the GPS sensor in the lid. It's like a sponge, and until you remove it, you won't get access to the electronics underneath. There are four long screws on the bottom side of the NAZA controller. You've got to take that apart, as there is a sensor module in there that is encased in water-logged foam padding.
Once it was dry, I put it in my toaster oven at 130° for 30 min. It was mildly uncomfortable to hold, but not painful. I installed the battery, and presto, everything was working 100%.
I never "rinsed" it - despite having mucky muck from the lake. I don't know how that relates to chlorine and calcium in pool water, but in my case, none of the solids were electrolytes - and I had no damage.
Now, as for the motor, it would seem the ring and spacer are not required for the motor to remain together, and functional - even under 100% power and load. My unit had a rattle inside it (like a loose screw) from the moment I opened it on Christmas morning. Tried shaking it out through the battery door, as I didn't want to take apart a brand new gift. But, that'll teach me. I'm sure it's been flying all this time with just the magnetic force of the stator/rotor holding the motor together, and the brass spacer ring finally found its most vulnerable target.