No problem with the controller detached. I have an entire table of Fastrack command switches that way.
Again, the known issue is- the aux power, track jumper, and GND, have been known- especially on O-72 switches to have come from the factory out of order compared to the label. You have not stated how you are powering the switch logic- either via track jumper or aux power in.
Again, I've seen there the actual internal order inside the switch was wrong, so then connecting aux power or even just replacing the track jumper shorts or fails to power the switch logic inside. Track jumper is literally a wire from the center rails inside the switch to that screw terminal, and then the jumper is supposed to connect that to aux in which powers the switch logic. However, if the order was wrong, possible errors include shorting aux in to GND or Track to GND which then would smoke that tiny wire inside (some of my pictures from earlier).
