The hookup guide states:
In addition to USB and battery connectors, the VBAT, and VUSB pins are all broken out to the sides of the board. These pins can be used as an alternative supply input to the Thing Plus.Looking at the schematic I see no protection between the V_USB input and power from the USB connector.
If I need information from the system I would plug in a USB cable, which would feed power from the USB cable
as well as the PS I have attached to V_USB.
Shouldn't there be a Schottky Barrier Rectifier in this circuit?