Has there been any resolution to this? I have the same problem with all my 4 Pycom circuits - I have both GPy and WiPy circuits and Expansion board 3.0. It happens even if there is no program loaded. It happens with or without the Expansion board. If I cover the circuit in my hand, it does not happen. If I remove my hand, it starts core dumping again. So it has to be an electrical problem of some kind.
Any idea why, and how to fix it?