MP Error loading firmware

I am trying to load new firmware onto an Airbot F4nanoV6 board. I have arducopter firmware on it now, but I believe it is firmware for another board. It seems to run with this firmware (OmnibusF4), but I cannot get I2C to work and I believe I need to flash it with OmnibusF4 nano V6 firmware.

I run MP, go to install firmware, ask for all options, fill in version 4.0.7, arducopter_with_bl.hex, then request upload. The operation starts with download from internet, but seems to have an error when it starts to try to load onto the board. Error is show in the jpg.

Go here and download the .apj file. Then use Mission Planners Load Custom Firmware option to install it.
Omni F4 Nano V6

Thanks. I was able to load the firmware using DFU. I am not familiar with how to handle .apj files.