Thoughts
Stoplight works again. We are so back.
It’s unclear if it was actually broken or if I just needed to plug it in to my computer to reflash the firmware with an updated WiFi username and password. But I opened it up and replaced a flaky relay and reflowed a couple of my awful soldering joints to make sure everything was grounded. (It’s possible the aforementioned flaky relay was actually just a victim of my awful soldering joints, but it’s been replaced anyways.)