Need response from a Castle tech for MMM question

[BrianG]

Well, if the polarity was ok, I guess it could have been overvoltage. A 5-cell rx pack can be close to 7v right off the charger (~1.4v/cell). Usually, the caps have some sort of safety margin so I wouldn't think that would be it.

Unless the removal of the components wasn't quite done right and a couple pads were bridged putting the full battery voltage on the BEC line. That would definitely cause the rx pack to get hot, and the voltage would be high enough to pop those caps.

BTW: the larger device does look like a cap, but the upper one looks like it might have been either resistor, cap, diode, or any two-terminal device.