How to fix “status_sec_img_too_large” error and flash any official rom.

To unlock bootloader and flash any other official firmware rom you’ll need to do the following:

  1. Install USB drivers.
  2. Install SP_Flash_Tool
  3. Download official developer ROM.
  4. Download cust.img and replace it in the ROM you’ve just downloaded.
  5. Flash your device using SP_Flash_Tool

Another working solution could be holding a volume button down while the software located the appropriate drivers.

Can’t change the region in the settings.

  1. Download cust_global.rar
  2. Unpack it
  3. Run this command
    fastboot flash cust cust.img
  4. Another way is to flashing your device again using Flash Multitool or MiFlash

It shows me only a black screen and nothing else.

This is actually a native recovery screen.

How to make wipe using a native recovery?

It’s not possible. You can wipe all data by resetting to factory settings.