I took a few more pictures of the failed boards and sent them to the fantastic people at circuits.io. They have very generously offered to send me new ones at no charge Hopefully these new boards will work out.
I also had a quick go at getting one of the boards working. After soldering lots of wires on the bottom of the board I powered it up and let the magic smoke out of my voltage regulator, so it looks like I may have a crook connection somewhere. It could also be because I didn’t have the right regulator available so tried another with a slightly different pinout. I put some heat shrink over the input lead and bent it into the right position. Maybe I didn’t get it quite right. The interesting thing is that the Mac I had it plugged in to didn’t complain about the device drawing too much current, so I don’t quite know what went wrong. Time to head out to Jaycar and get the part I actually need I guess