Hypothetically,
I'd start with the fuse...
I'd test any nodes with a known good ssc on a known good port on the hub
After correcting the wiring, I would check the input terminal for12v and then check the output of the 5v and 3.3v regulators wit no strings attached.
If everything so far passes, hook up a single node or a short string.
What could be dead - fuse, 5v reg, 3.3v reg, 485 chip, PIC, string...
No electrolytic caps, so all the capacitors should all be fine. Resistors don't care which way the current flows.