Technicians often extract the preloader_cattail.img (the codename for the Redmi 9C) from a working stock firmware. When using the SP Flash Tool to unbrick the device, this specific file is often loaded into the "Boot" tab. It instructs the tool on how to handshake with the device's hardware to push the full ROM. In essence, the preloader file acts as the key that unlocks the door for the repair software to enter and fix the house.
: If your device is stuck in BROM mode (Black Screen) or won't turn on, a custom or stock preloader is often required to re-establish communication with tools like SP Flash Tool . redmi 9c preloader file