Hi Pete, sorry to hear that you had to go through such trouble to figure out the problem. From your description, I just checked and realized that it’s partly our fault because the MOSFET is supposed to be a MMBT3904 transistor but we substituted it with a 2N7002 MOSFET without realizing that this particular version doesn’t have a pull-down resistor. We did test all VIN-GND and VCC-GND resistances of the partially assembled boards and did not find any issue. But given that now the weather is dry and static electricity is high, it may have caused yours to trigger the MOSFET. Anyways, it’s great that you find out the cause. Thanks.