MC7430 load firmware

We have a few hundred MC7430 modems and want to load new firmware onto them. In order to do this do we require a Development kit? If so, is the Development Kit for these units still available? Once we connect to the modem how would we load the new firmware onto it?

Did you check with distributor about dev kit?
You can use the exe file to upgrade fw in windows

How would I connect the modem to a windows machine?

there is USB connector in the dev kit

I don’t have that type of model, but you could try qmi-firmware-update command from libqmi-utils / libqmi package. I used this command on which is based on Arch Linux, as of April 2023. I used qmi-firmware-update command on MC7750. I think you should also try and use commands from SLQS04.00.23-lite.bin.tar.gz or from SLQS04.00.23.bin.tar.gz.