You need to Download Fastboot ROM which comes in .tgz format. Go through the below link & Download Fastboot ROM of your device
Redmi 4 Miui9 Flash File:
1. Download Redmi 4 Fastboot ROM from above link and extract it on your computer.
3. Make sure that you have installed proper USB Drivers. Also, Make sure that you have Unlocked Bootloader of your device.
4. Now, Open Mi Flash Tool Application from Start Menu. Now, Click on the “Select” button & choose the folder of extracted Fastboot ROM. Refer Screenshot give below.
5. Now, Connect your Xiaomi device into Fastboot Mode.
6. After booting into Fastboot Mode, Connect your Redmi 4 to the computer using USB Cable. If you have already installed the driver then its ok else Windows will automatically install them.
7. In Xiaomi Flash Tool, Press “Refresh” button this will show your device is connected or not. If it shows your device then go ahead. If not then installed Proper ADB & Fastboot Driver.
8. You need to choose any Flashing Option from the following. Refer the Table below & choose one which is suitable to you.
9. Select any option & Press “Flash” button to start flashing process.
10. Now, It will automatically Flash the required files on your device. This will take few minutes for installation.
11. You will see “success” message after installation is completed. That’s It & Congratulations! We have successfully Flashed MIUI Fastboot ROM using Mi Flash Tool. Now, It will automatically Reboot your device. If not then Remove Cable & Power on it.