@jcaron Isn't this the opposite of what what stated here: Not completely the opposite, it's still more efficient to use a regulated 3.3V supply (low voltage forces the onboard regulator into bypass ECO mode) But it needs to be updated to reflect that 3.3V should be applied to the 5V/VIN pin. Is the Pysense/Pytrack sending power to the module via 5V Yes, all the various shields implementing deep sleep control the *py board's 5V rail

The same USB cable works fine with all other LoPys so I don't think it is a problem related to the cables nor the USB ports...