Okay, here's an update you've been waiting for:
The banana pi IS DEAD
2 days in, the SoC shorted and probably burnt itself. It's likely to be my fault, but is painful either way.
Resoldering the diode didn't bring it back to life...
On the better side, I finally got Mezzano to boot on my dual-xeon machine. Single-core, deactivates mouse and keyboard, incredibly slow. But I can easily fix the first two. This is also why I had the downtime. I was too sick to get the server back up earlier.
@iska
It might get very complicated at this point, opening a dispute is easy before confirm you've received that package in full, but now — I don't think they have a set procedure like Amazon does.
You can try contacting the merchant, but they would likely tell you to destroy it — sending it back is most likely simply not worth it, they might make you a discount on another unit, but might as well not 🤷