Xiaomi smartphones are famous for their availability and functionality, but sometimes users are faced with the need to reinstall the software. the Redmi 9 NFC (codenamed merlin) is no exception, and it has the same recovery procedures as other devices of the brand.
The process of replacing the operating system requires careful and strict follow-up to instructions, as incorrect actions can lead to the failure of the device. In this article, we will discuss in detail all the steps from tool preparation to installation of custom recavator.
There are several ways to restore and update software: through the built-in menu, through Recovery mode, and through Fastboot mode using a computer, each with its own characteristics and application depending on the current state of the device, choosing the right method is the first step to a successful result.
Preparation for flashing and necessary tools
Before you start active action, you need to prepare the workplace and software, and without prior preparation, there is a high risk of interrupting the process in the middle, which can lead to data loss or "bricking" of the gadget. You will need a Windows computer that is working properly. USB-cable and stable internet connection.
A critical step is to back up all of your critical data. The firmware process often involves cleaning up your device's internal memory completely, saving contacts, photos and documents to an external drive or cloud storage, and making sure your smartphone battery is at least 60 percent.
- 📱 Charged smartphone Redmi 9 NFC (minimum 60-70%)
- 💻 Computer or laptop with Windows operating system
- 🔌 Original or qualitative USB-data-line
- 📥 Installed drivers ADB and Fastboot
⚠️ Note: Use of unoriginal or damaged USB-cables can cause communication to break down during system file writing, which is fatal for the device.
To work, you will need to download the current firmware image. Official files are available on the portal miui.com or proven resources like xiaomirom.com. It is important to choose a version strictly for the model codenamed merlin, as firmware from Redmi 9T or Redmi 10X 4G may not fit or damage the hardware.
Unlocking the Bootloader bootloader
Official firmware through standard recovery is only possible if you are upgrading to the same regional group version.To change region (for example, from China to Global) or install custom builds, it is mandatory to unlock the bootloader, a procedure that Xiaomi makes mandatory for the protection of user data.
Unlocking requires a Mi Account tied to the device and a special utility Mi Unlock Tool on the PC. The process is not instantaneous: after submitting an application in the phone settings, you need to wait from 7 to 168 hours (usually 7 days), only after this time the tool will allow unlocking.
Why do you have to wait 7 days?
Once you get permission, you need to put your phone in Fastboot mode, holding the power and volume buttons at the same time when the device is turned off. Connecting your smartphone to your PC, launching the utility and following the instructions on the screen. Remember that unlocking the bootloader automatically performs Wipe Data, deleting all files.
⚠️ Note: After unlocking the bootloader, some banking applications and services with a high degree of protection (Google Pay, bank keys) cease to work, as the integrity of the security system is violated.
Some users try to use third-party unlock methods without waiting, but they are often unstable and can lead to the blocking of the Mi Account.
Installation of official firmware through Recovery
The easiest and safest way to upgrade or restore a system is to use the built-in Recovery mode.This method does not require an unlocked bootloader if you are installing an official firmware in the same region. The firmware file should have the.zip extension and weigh about 2-3 GB.
Copy the downloaded file to the root of the smartphone’s internal memory. Then go to the update menu and select the file manually. If the standard menu doesn’t see the file or gives an error, you’ll need to log in to Recovery mode via a button combination.
☑️ Checklist for firmware through Recovery
To enter Recovery mode on your phone turned off, press the volume and power button. In the menu that appears, select a language (usually English or Chinese), then press Install and specify the path to the archive. The process will take from 5 to 15 minutes.
| Parameter | Recovery Mode | Fastboot Mode |
|---|---|---|
| I need a PC. | No (file on phone) | Yes (required) |
| Unlocking BL | Not always. | I'll be sure. |
| Difficulty | Low. | Medium/High |
| Risk of error | Minimum | Medium. |
If you have an error message or it freezes during the installation, don't panic. Most often, the problem is a corrupted firmware file or version incompatibility, and then you should try to download the image again.
Fastboot and Mi Flash Tool
Fastboot firmware is considered the most reliable method for deep system recovery, as it allows you to completely clean all memory partitions. This will require a firmware archive in.tgz format (unpacked) and the Xiaomi Mi Flash Tool program.
Run the program on your computer on behalf of the administrator. Put your smartphone in Fastboot mode and connect it with a cable. In the Mi Flash Tool, the device must be determined, and its serial number will appear in the status bar.
fastboot devices
fastboot getvar allIn the program interface, press the button. flash_all or flash_all_lock. The first option will simply stitch the system, the second will stitch and re-lock the bootloader (use only with the original firmware!). The process of writing sectors will take a few minutes, after which the phone will automatically restart.
💡
If the Mi Flash Tool gives an error "Flash All Lock" on the unlocked bootloader, use the command "Flash All" without locking, otherwise you will get an anti-rollback error.
It's important to keep the cable on and off until the Success message appears. Even if it seems like progress is in place, the program can perform background operations on memory partitions, and interrupting at this point is a direct route to the need to solder the programmer.
Installation of custom TWRP Recovery
For advanced users who want to get super-user rights (Root) or install custom firmware (LineageOS, Pixel Experience), you will need a third-party recavator. For the Redmi 9 NFC, the best choice is the TWRP (Team Win Recovery Project), adapted to the MediaTek Helio G80 processor.
Installation is done via Fastboot mode using the command line. You will need a twrp.img image file that you need to put in the folder with the ADB tools. The installation command looks standard for Android devices.
fastboot flash recovery twrp_merlin.img
fastboot boot twrp_merlin.imgAfter the command is executed, the phone will immediately boot into the TWRP menu. Here it is important to immediately back up the current system (Backup), if necessary, and only then start installing new zip archives or cleaning partitions (Wipe).
⚠️ Attention: When installed TWRP Data Encrypted Devices may require Format Data partition formatting, which will delete all files, including internal memory.
Castomic recaps allow you to install modified cores, patches to improve sound or camera, as well as make full backups of the system (Nandroid Backup), which are restored to exactly the state at the time of creation.
Possible errors and ways to eliminate them
In the process of firmware Redmi 9 NFC There are a variety of errors that can occur, from simple communication failures to critical failures, and one of the most common problems is the Mi Flash Tool 102 or 2004 error, which is often solved by replacing it with a new one. USB-port on the computer motherboard (use ports at the back of the system unit) or disabling the digital signature check drivers.
If the phone went into an endless bootloop after a failed firmware, try logging in to Recovery and doing Wipe Data/Factory Reset. If that doesn't work, you'll need to re-running through Fastboot with a full cleanup.
There is also a driver problem where the computer simply doesn’t see the phone in Fastboot mode or ADB. Windows Device Manager may display an unknown device with a yellow exclamation point, in which case you need to manually update the driver, indicating the path to the folder. xiaomi_usb_driver.
In rare cases, especially when experimenting with (partitions), recovery through EDL mode (Emergency Download Mode) may be required, which allows you to flash the phone even with a completely broken bootloader, but requires an authorized Mi Account or a special box for repair.