NOTES- First prepare a Laptop or PC with adb and fastboot drivers installed. Log-out Google account and xiaomi account and remove screen lock to avoid FRP issues. Charge your device 50%+ Use official cable to avoid failures.
STEPS Reboot you device to bootloader [FASTBOOT] mode. Connect it via your PC or Laptop. Flash the stock CN rom first that i given in ROM post, via Flash_all.bat or Mi Flash tool, if you are going to use Mi flash tool i will suggest to use 2018 version to avoid issues. Now after flashing and booting stock Cn go to booloader mode and open the MOD rom folder and run the flasher.bat, it'll ask some questions just type y and enter. after flashing you device will boot normally.
ROOTING PROCESS & Removing FRP lock. I've given a patched vendor_boot in rom folder, if flasher tool doesn't flashes it just go to bootloader mode and type cmd, fastboot flash vendor_boot vendor_boot.img IMG is by default patched with KernelSU Next. Use this manager: https://github.com/KernelSU-Next/KernelSU-Next/releases/download/v1.1.1/KernelSU_Next_v1.1.1_12851-release.apk FRP removing: i told you to remove google account and screen lock to avoid FRP issues, but if you forgot it and now you got caught by FRP lock, here is method to remove. first boot your device to bootloader mode and after that run cmd, fastboot erase frp. and when it's done just reboot your device normmaly.