How do I know the process of downloading firmware is working?

When doing a Firmware Download, even though the PC is proceeding and showing it is sending data, that is no guarantee that the unit is actually receiving it. Because multiple units can be daisy-chained together and updated at once, there is no feedback going to the PC to acknowledge the unit is receiving the data. The only way to tell it is receiving the data is to watch the front panel of the unit. When the PC indicates it is switching from downloading the PIC code to Erasing the FPGA to Programming the FPGA, you should see the same indications on the front panel. If you don’t see the front panel switch to say it is Erasing the FPGA at the same time the PC says it is Erasing the FPGA, then the download has already failed.

The final way to know that the download was successful is that the unit will reboot itself at the end of the process. If the PC indicates it is finished, but the front panel still says it is Programming and has not rebooted, and you have to unplug it to get out of the programming mode, then the download failed. If the unit reboots itself without having to do anything, that is the sign that the download worked as it should and should successfully have the new version.