matapan

I was able to use the original 32GB card.
Here is the executive summary: Use a Windows PC to format the SD card and to copy the firmware files to the card. If you are a Mac user, you may experience the same problems I did if you decide to go the route of using MacOS disk utility. For whatever reason, the ISY will not read the card and report an error by flashing its red error light.
Read further if you want some details.
I first tried formatting the 32GB SD card in MacOS Disk Utility in FAT32 format. I subsequently copied the firmware files to the SD card, ejected it and installed the card in the ISY. This resulted in the controller starting up and reporting an error.
Next, I tried formatting the card in the ISY itself from the ISY shell. The format operation curiously did not complete with the expected completion message. I was reluctant to try copying the files and trying to boot with the card.
I then ordered a 16GB SD card, formatted it in Disk Utility, then copied the files to the card and tried it out in the controller. No joy. Same error. Since I had access to another SD card from which the controller would boot successfully, I tried cloning the card using Disk Utility, creating a dmg file from the known good 4GB SD card and writing the image on to the 16 GB card. Again the ISY complained about the cloned card as well. I tried Balena Etcher to write the card from the image created again to see if that made any difference. It didn't.
So I tried making a bit for bit copy of the working card to an image file using the dd utility, then I tried the cloned SD card in the ISY. Same error.
I was out of ideas other than what Geddy suggested. So I tried formatting the 32GB SD card on a Windows laptop, copied the files to the card and tried this out. This worked.
I don't know what the subtle differences are in the FAT32 formats on Windows and Mac, but I think there is one. If anyone is going to try a bit for bit copy of a card, try using the same size card.
Just take the easiest route and find a Windows machine. You will save yourself a lot of time and headaches.