The PCB is not your worry- I've done a full dog-dish-dunk with an S107, and shook it out, kept flying. The board has conformal coating, or it's sealed, or just plain not affected.
However...water inside a Lipo is a "very bad thing
". I do believe they're sealed up good, but...it's to be known.
A good example of how much abuse a lipo will take.