Hmmm, sounds like a flight gone bad for sure! Best way I've found to make sure a motor is clean is disassemble it, they really aren't very difficult to take apart and it's the only way to be absolutely certain you got all the dirt out. Usually all you need to do is take the circlip off the shaft and slide it and the bell off the inner housing then clean as needed. If it's really packed in you can use some electrical contact cleaner from Radio Shack or the local auto parts store.
A damaged lipo can easily be decommisioned by submerging it in salt water for a week, to discharge and chemically deactivate it, after that it can be tossed out with the regular household trash. Or you could take it to a remote location and intentionally short it out to see first hand what happens when a lipo ignites, it will certainly give you a healthy respect for what these things can do when they go bad.
Last time I stuffed one into the ground was just a few short weeks ago when the Hoverfly had a motor stop working about 160 feet in the air. When I got to the crash site all I saw was one arm sticking up out of the two feet of snow on the ground with the motor still running. I had to pull the qaud out of the snow and stick the spinning prop and motor into the snow so I could grab the battery connector and kill the power. Amazingly after I got all the snow out of it and let everything dry out thoroughly all of the electronics worked but I eventually replaced one of the ESC's as it started acting flaky soon afterward.
I'm always impressed with how much abuse one of these things can take and need only minor repair afterward, if I had stuffed one of my gasser helis into the ground from 160 feet up there likely wouldn't have been much left worth saving!
Ken
