As you may know, there are two FUNcube Dongle models out there, the original FUNcube Dongle Pro (aka FCDP, serial numbers below 10000, firmware v18x where x is a release letter, with v18j the most recent) and the newer FUNcube Dongle Pro+ (aka FCDPP, serial numbers 10000 and above, firmware v20.xx, with v20.03 the most recent).
FCDPPs shipped since about November 2012 with serial numbers 10250 or so and above already have the latest 20.03 firmware shipped with them, so there is no need to perform an update. (The only other public version in the very early FCDPP units were inadvertently sent out with FCC cellular blocked frequency ranges, other than that they functioned perfectly well).
Although the names of the two FUNcube Dongle models are similar, they’re almost entirely different hardware designs, and the firmware designed for an FCDP won’t work in a FCDPP, nor the other way around.
When I wrote the bootloaders for the FCDP and FCDPP, I didn’t include a check to ensure the right firmware files were for the correct FCD. Next time I will! There should be no harm if you inadvertently upload the wrong firmware, but the unit should simply remain in bootloader mode until a valid firmware image is uploaded. Both the FCDP and FCDPP include several safety mechanisms both in software and hardware to perform a sanity check in case the firmware’s wrong, and if it makes no sense the device will sit in bootloader mode to prevent “bricking” the device.
So in short if you’ve recently purchased an FCDPP, you shouldn’t have any need to update the firmware.
Many thanks, Howard