Yeah, sand is all but impossible to keep out of your stuff. tape the bearings and extra motor holes, and silicone the rear where the windings exit the can. Snad is a very harsh environment.
For your motor...can you spin it by hand at all?
Yes it spins relatively freely (just a SLIGHT bit of binding) but then again I dont remeber how much friction there was from the rotor when I first got it.
Welcome to Florida, or sand country. I have never seen any other type of dirt here besides sand. It's everywhere you go and it makes your truck loose traction fast. But hope you get your motor running again.