Complicated firmware question V9-Z9mini

maybe not so complicated but hard to summarise in a title:
I have a z9 Mini. Its control board failed, so I bought a replacement “V9/Z9mini” board. It has “V9” firmware in it (obviously won’t run the miner, but it does run the firmware).
Can I use the HiveOS SD card method to force install?

I’ve tried the web and SSH methods, and both check and find V9 type and stop the process.

If not, where can I find a pre-2019 copy of Bitmain’s stock Z9mini firmware (without the SSH access removed)? I presume I can SD-card method that on, then flash HiveOS.