I also got "Bad Code" message when I was going to upgrade the DSP8000 Anniversary speakers.
It turns out that the SE firmware is not intended for these speakers and I had to get a special firmware.

Same I guess for the old DSP8000 before Anniversary and SE series was released.
But Meridian impress me that even with wrong firmware, the firmware upload program could still identify the type and I could easily flash back the old firmware.
Hope it sorts out for you.

Meridian owner since 2012