OK – some good progress. I downloaded an older version of Quartus Programmer (linked here http://www.firebrandx.com/nespalette.html) and installed it, along with older USB Blaster drivers that were included. My clone does work with these drivers. I was able to successfully detect the FPGA and program the latest 0.78 FW. After disconnecting JTAG and power cycling, my LCD now shows an OSSC FW version message!
I don’t really understand why programming was necessary, unless the pre-programmed IC that came with the kit had invalid FW?
Unfortunately, I get no test pattern on the HDMI output – but I have only tested with one monitor. If I connect a SNES over SCART the OSSC can detect and sync to it correctly, but still no output image.
Without an IR receiver all I can do with the unit is change sources, I have no access to menus so I don’t know if some option needs to be changed.