The issue with me saying the edit, is that they won't provide you with any support, and you won't have the ability to fix it yourself without any help if something were to go wrong. And I sure can't help because I didn't have issues so I wouldn't know even how to help you.
But, the files they provide can be opened with notepad, one has a check for your model ID of the s9. It's looking for S9i. Any other model that gets returned, throws an exception and won't install.
It's an alpha firmware anything can get screwed up and become unrecoverable even if you follow the instructions to the letter. It's run at your own risk.
The file that you edited was in the firmware folder and was called Control and it was the top line for anyone else that wants to know.
To get it working there are two options
1) testing with an SD card, it doesn't matter what firmware you are running on the controller it will boot and run from the SD card.
2) Flashing directly to the control board, the miner must match what is in the control file mentioned above.
To flash you cannot be running the firmware from the SD card, the scripts do not copy any data from the SD card and only from your computer. You can either run it from the SD card where settings are not saved after reboot OR you can follow the instructions for flashing the control board with the braiins os.