1) First of all, your battery pack was not sealed, might have leaked outpower (has nothing to do with it but seal it next time)
2)don't submerge the motor
3)don't submerge the battery pack
4)The blue ESC is the only waterproof XL-5
5) don't try to overtest the waterproof system, they mean "water resistant"
6) once again, DON'T SUBMERGE!!!
7) use plastic dip to seal the battery
8) use silicon gell to seal the speed control, the radio box to seal the radio, and silicon gell to seal the servo