They ended up with a gender bender cable. It was supposed to always stay attached to 1 bit of kit. That kit could run on 7-48V. Unfortunately, they unplugged it from the wrong end. When they plugged it back in, they put it into the 2nd power source connector. A 28V lipo was wired directly into a regulated 12V bus. That bus apparently was also connected to internal parts, and wasn’t protected against backflow (defence in depth failure). Magic smoke was lost.
Did they use the same style and gender of connector for both power and signal?
They ended up with a gender bender cable. It was supposed to always stay attached to 1 bit of kit. That kit could run on 7-48V. Unfortunately, they unplugged it from the wrong end. When they plugged it back in, they put it into the 2nd power source connector. A 28V lipo was wired directly into a regulated 12V bus. That bus apparently was also connected to internal parts, and wasn’t protected against backflow (defence in depth failure). Magic smoke was lost.