MarkT:
NEVER short out capacitors like that - you may destroy the board. (LiPo batteries
will put out 50A or more compunction, enough to vaporize all the power traces).
Brain fart. Yes, that would be bad 
What I meant was put a resistance across them (eg. 1k) - see if the frequency of the noise changes.
Or try the pen trick. I didn't know that one.