if you can program the SSCv3 with test firmware, and it works... then your pickit3 is working.
if you can get the SSCv3 with test to do blinky, then your hub has power.
if you cannot get the SSCv3 or v4 to do blinky before getting the channel assignment (xlights test mode set to do ALL channels), then it sounds like your pixelnet isn't working (anything from computer to dongle, dongle to hub, ...)
if only one had problems, you might suspect a 485 chip, but not all of them... well, unless there was an assembly problem.
so...
check your computer to dongle:
make sure EtD magijack (silver connector) is connect to your network switch, or directly to your computer. make sure that your computer shows the NIC is enabled and reports a link. the computer should show transmitted packets -- and if you have a sending device, also received packets.
make sure that your cable connects from the black EtD jack to the smart hub, it should be connected to the pixelnet IN connector on the middle of the hub board. you should have a green light on the hub (that is a given since you have power for the test firmware to do its business)
what do you know about the hub? has it successfully worked before?
what do you know about the dongle? has it successfully worked before?
change out cables -- I've seen that cause problems too.