Ensure your PC recognizes MediaTek USB VCOM ports.
If your Redmi 14C has an unlocked bootloader and can still enter Fastboot mode, this is the official and safest method to restore the stock HyperOS/MIUI software. Prerequisites & Downloads A Windows PC and an original USB cable. (Latest version). How to Unbrick REDMI 14C
In the field, load the auth_sv5.auth file if provided with your firmware or tool kit. Step 4: Flash the Firmware Ensure your PC recognizes MediaTek USB VCOM ports