Hi lawrence_jeff,
during this week-end i think to receive a new official opengarage and i try to mount the sensor, and of course i send you some picture.
the GPIO4 and GND contact are located on the LEFT-TOP of the device.
i have installed your firmware on my actual opengarage and seems to work very well and much better than original firmware, but the interface have some difference with your screenshot, for example i cant see VEHICLE TRESHOLD field, it’s normal?