Sounds like a wire got pinched.. but it's not necesarely very visible, just a nick on the insulation is enough to ground the 12v and blow the transistor that turns it on and off on that port.
I didn't find good pictures of the PCB and i'm not going to rip mine apart to check ' but since the Octo turns off the 12V when there's no speed demand, there should be a tiny SMD transistor tied to the 12V pin for each port.
If you feel like poking about, you can check it with a multimeter if it has a diode check function (with the Octo not powered, and unplugged).
The transistor should measure as two diodes back to back. If you probe the pins 2 by 2, you should find two silicon junctions (forward voltage readings roughly in the 0.5 - 0.6V), but never any short. If you have a short between any two pins, the transistor is toast. If you can measure only one junction or none, the transistor is toast.
That's what i would look at, if indeed you have some speed demand within aquasuite. Should be failry obvious in the Fan tab for the Octo. on port 1, voltage should be at 12v, and some PWM % on the output.

haha, hey i studied electronics at the youtube university eh, but there's a few tips and tricks that will get you by for like 90% of issues. testing and changing caps, testing transistors, various diodes etc..

Even if we don't have the skills to repair, it can allow you to see if it's dead or not. SMD components are not fun to work with at home...