Try opening the case and clearing out any dust/crap inside. It might be shorting the bottom of the circuit board.
The combination of some minerals and small particles of metal can be conductive when combined with moisture. If that happens, then that does some weird stuff to the rather complicated electronics. Doesn't always fry it - just makes it a bit "rogue".
Obviously some of the dust and stuff that's on the track, finds it's way into the case, and a quick clean of the insides will usually clear this.
That's assuming its just that, and not a minor component that's gone pop. If it was a major component, it wouldn't work at all.
I don't know if opening the case voids the warranty on your equipment - only open the case if it's an emergency or you know its not covered.
If you don't want to open the case, try blasting it with compressed air (and I mean compressed air and not canned air which includes a liquid propellant), but unless you can see it's clean inside, you're never quite sure. (I'm actually saying that I wouldn't bother blasting it with air!)
If it's covered by a warranty, send it back, but be prepared for a wait...
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