If you can take some measurements of the fan, perhaps it would be possible for you to buy a replacement fan meant for another machine that has similar dimensions to yours and swap it in that way. Usually the motor is permanently attached to the frame of the fan but you should be able to pull the blade assembly off. Perhaps what you can do, is find another fan with a similar blade size, that also has a metal plate backing, and perhaps cut the excess off the new one, cut the motor coil bit off the old metal plate, and somehow install the new metal plate onto the old one.
Hmm. If it's gotten wet as some commenters have noted, then maybe it's best to take it apart and clean/dry any traces of that out first. Try taking the battery off of it and then leaving it for a while, and then plug the battery back in and see if it works.
See if the blades turn freely first. If they do, try taking it apart and checking the thermal fuse of the motor which will probably be wrapped into the coils somewhere near where the wires go in. Unfortunately it's a bit fragile since the wires are thin, so you'll probably have to exercise caution.
Have you tried connecting the device to your computer, backing up all of your information, and performing a factory reset? It seems like half of your issues are coming from a software glitch which might be resolved by a reset.
Perhaps you might start by removing the top panel; usually it will pop off the top and is clipped in. Under that, it should become more evident how to proceed further. perhaps take a picture for us once you get there?