I’v got firmware updating troubles as well.
My brand new C2500 showed up with version 1.61 & it appears that the CDM48 delivered with it has with version 1.41. The desk recognizes the USB stick, but the message I get is “firmware not found”. I’ve tried every which way (following the instructions of course) to load the firmware onto several different USB sticks (formatted to FAT). I’ve never had firmware update issues with my other S5000 / DM48 desk…..
Grrrrrrrrr