If you want to make your own Unicard, you must load bootloader into the Unicard for a firmware update from an SD card. The DFU file (a binary file for loading the bootloader for a firmware update from an SD card) is available along with the source codes of the firmware Unicard on sourceforge:
DFU binary file of the bootloader.
DFU downloader for OS Windows.
When updating firmware MZ_ID firmware is not checked (to still allow the option of changing the Unicard firmware from one type of computer to another). Incorrectly matching firmware with a computer, on which the Unicard update is being done can damage your device.