Try to take it apart "down to the next layer"... the leakage may have gone beyond what you've already seen.
If it has, clean that, then try it again. If it still doesn't work, go down another layer and repeat if necessary. At some point, you may get to something that looks like a printed circuit board... that's where you probably shouldn't use the dremel.
You could try putting some club soda on a Q-Tip at that point and cleaning off any visible corrosion... or you could take it to a professional and ask if they've ever revived one. Good luck.