Some basic troubleshooting

I'm no expert in USB or Linux, but here are a few debugging things which might be useful for others trying to get the arm working.

1.  Is it switched on!  Without the switch in the on position the device won't show up - should be obvious but is of course worth checking!  I also think if you leave it on doing nothing it seems to switch itself off (although thats an assumption because it seemed to need "reset" this morning).  This also means that dead batteries will presumably mean no response from the device.

2.   Run lsusb at the command prompt.  You should see something like this amongst the response:

Bus 002 Device 022: ID 1267:0000 Logic3 / SpectraVideo plc

3. If you are having problems then the command dmesg may help diagnose the problem, although where to start may not be easy - but here's what a working system reports with dmesg | grep USB reports:

[ 1845.033134] usb 2-1: new low speed USB device using uhci_hcd and address 4

If you disconnect the cable and run again you will then see

[ 1952.176133] usb 2-1: USB disconnect, address 4

4. If the light works but the motors don't (this happened to me) it is probably a wiring problem.  In my case the single orange wire had come disconnected from the "pins" on the board and just needed slipped back on.