Some time ago, atalax reversed the protocol used by KBT Pure Pro for flashing its firmware in a hope of being able to flash a custom firmware (or do some BadUSB demonstration). This script is able to upload a firmware binary onto the keyboard.
The binary is obfuscated (already solved on SE) The firmware has a trailer and a 32-bit checksum. If the uploaded firmware checksum does not match, the keyboard stays in the bootloader.
The MCU used is Nuvoton NUC122, which has a standard SWD interface.