Had the same thing happened to me with a SeaEra motor. Pulled the motor and opened it up and the armature had some corrosion
on it. Cleaned it, sprayed WD 40 inside and put it bact together and it has worked fine ever since. Every time I am on the boat, I push the button just to make sure it gets turned on and running. I also replaced the motor in another head and the newer motors are definitely quieter than the old ones.
I suspect that sea water
got into the older motor, hence the freezing up, but it has run fine after I cleaned it up.