Owning a Xiaomi smartphone often involves experimenting with software, but there comes a time when you need to return the device to its original state.Closing the bootloader on the Redmi Note 9 Pro is a critical procedure for those who plan to surrender the gadget under warranty, sell it or simply protect the system from unauthorized changes. The reverse process requires care, since any error in the stage of working with low-level commands can lead to the failure of the device.
Many users mistakenly believe that simply flashing the official MIUI version automatically blocks the bootloader, but this is not always the case. The system may work stable, but the unlock flag in the bootloader will remain active, as you see when the device starts, which is why it is important to execute a specific algorithm of actions that will force the controller to close, returning the phone to factory safety parameters.
Before you start taking action, you need to be aware of the risks. The operation affects the system partitions of memory, and interrupting power or disconnecting the cable at the wrong time is fatal. The process of closing the bootloader on the Redmi Note 9 Pro requires the presence of the original firmware corresponding to the region of the device, otherwise there will be a risk of obtaining a “brick”. USB-Cable and make sure the battery is at least 60 times charged%.
Why you should block the bootloader on Redmi
The main reason Redmi Note 9 Pro owners are eager to close the bootloader is to restore warranty obligations. Xiaomi service centers often refuse free repairs if they find an unlocked bootloader, considering this as an interference with the software part.
In addition, a closed bootloader ensures the integrity of Android security. While the bootloader is open, it is theoretically possible to access secure memory areas where biometric data and encryption keys are stored. Some banking applications and services with a high degree of protection can limit functionality or even refuse to work on devices with a broken trust chain.
⚠️ Warning: After locking the bootloader, all data on the internal drive will be permanently deleted. The system will force a full reset (Wipe Data) as a measure of protection against device theft and substitution of system files.
Also worth mentioning is the stability of the work: official security updates and new versions. MIUI They come to devices with a closed bootloader in priority and install without signature verification errors. OTA-updates, requiring manual flashing through the computer.
Preparation of equipment and software
The success of the operation depends on the quality of the workspace. You will need a computer running the Windows operating system, because the drivers for Xiaomi and the tools Fastboot most stable work in this environment. Using virtual machines or operating systems like macOS or Linux is possible, but requires additional settings and can lead to unstable connection.
It is critical to install the current ADB and Fastboot drivers. Without them, the computer will not be able to communicate correctly with the phone in boot mode. You also need to download the official firmware for your particular model. For the Redmi Note 9 Pro (codename curtana), it is important not to confuse the version with the Redmi Note 9 or Note 9S, since the firmware is not compatible.
☑️ Checklist of preparations
To work with firmware files, you will need an archiver that supports the.tgz format, for example, 7-Zip Or WinRAR. After you unpack the archive, you should see a set of files, among which will be an executable script. flash_all.bat or flash_all_lock.bat. The last file is what we need, because it contains a command to lock.
Installation of drivers and setting up the environment
The first step is to install drivers. If you haven't previously connected your phone to debugging or Fastboot, Windows may not recognize the device correctly. Download the SDK Platform Tools package from the official Android developer site. Unpack the archive into the root folder of the disk, for example, in C:\adb, so that the path does not contain spaces and Cyrillic characters.
After installing the tools, you need to activate the developer mode on the smartphone itself. → About phone and seven times quickly click on the item Version MIUI. You will receive a notification that you have become a developer. Then in the advanced settings, activate the items. USB-Debugging and Factory Unblocking.
- 📱 Connect your phone to your PC and allow debugging in the pop-up window on your smartphone screen.
- 💻 Check for device availability in Windows Device Manager (Android Device section).
- 🔌 Transfer the phone to Fastboot mode by pressing the Volume Down and Power buttons simultaneously.
- ✅ Make sure the Fastboot status bar on your phone has orange text on it "FASTBOOT".
If the computer makes a connection sound, but the device in the Manager is marked with an exclamation mark, you need to manually update the driver, indicating the path to the folder with the ADB drivers installed. Proper installation of drivers is the foundation without which further steps are impossible.
Flashing process with loader lock
Now, to the most critical point, make sure that the phone is in Fastboot mode and connected to the computer. Open the folder with the unpacked firmware. Inside it should be a folder with the system image. Find a file with the name. flash_all_lock.bat. It is this script that contains the command. flash_all_lock, which re-flashes all sections and closes the loader.
Double-click the file, and you'll see the command line that starts the automatic firmware process, and you'll see the progress of the boot, recovery, system, and other partitions, and it takes 300 to 600 seconds, and you're not allowed to touch the cable or interrupt the computer.
fastboot flash boot boot.img
fastboot flash recovery recovery.img
...
fastboot oem lockAt some point, a warning may appear on the phone screen that the device will be reset. This is a normal situation. The script will execute the oem lock command itself, after which the phone will restart. The first boot after locking the bootloader on the Redmi Note 9 Pro can last up to 10-15 minutes, as the system encrypts the data again.
⚠️ Note: If there is an error in the process of firmware "FAILED remote: device is locked or similar means you are trying to close an already closed bootloader or using incompatible firmware.
What do I do if the process is stalled?
Solving common mistakes and problems
Even with careful preparation, failures can occur. One of the common problems is error. FAILED: remote: flash write failure. It indicates that the script cannot write data into memory. USB-- Cable or port. Try to switch the cable to port. USB 2.0 (black), located directly on the motherboard (back of the system unit), bypassing the front panels and hubs.
Another common mistake is that the firmware and device region mismatch is not the same: If you try to close the bootloader with global firmware on a Chinese bootloader or vice versa, the process may go well, but the phone will go into an endless bootloop, which will require re-routing through EDL (Emergency Download Mode) mode, which requires an authorized Mi Account or special boxing.
The table below will help you quickly diagnose the problem by the error code or symptom:
| Symptom/Error | Probable cause | Method of decision |
|---|---|---|
| The command line closes instantly. | Wrong path to files or lack of drivers | Check the path, reinstall ADB drivers |
| Error "signature verified failed" | Inconsistency of firmware version | Download firmware strictly for your model and region |
| The phone hangs on the Mi logo | Failure to encrypt data after lock | Run Wipe Data through the Recovery Menu |
| Fastboot doesn't see the device | Problem with cable or port | Replace the cable, change the USB port |
💡
Use only the original cable from the supply kit. Cheap charging cables often don't have the necessary contacts to transfer data in Fastboot mode, leading to a communication breakdown at a critical moment.
Checking the status of the loader and final actions
After you successfully restart and set up the system first, you need to make sure that you've achieved your goal. Turn off your smartphone completely. Then press the combination of the Volume Down buttons and Power buttons until the Fastboot logo appears. Take a close look at the screen. If you see an image of a hare repairing an android and the FASTBOOT label, look at the color of the text.
If the bootloader is closed successfully, the word "FASTBOOT" will be black or gray, and below the orange warning "unlocked" will be displayed. Also in the status bar can display the icon of the lock, which means that the chain of trust is restored and the system is ready for full operation with a guarantee of security.
- 🔒 Make sure there are no unblocking warnings in the About Phone menu.
- 🛡️ Check Google Pay and banking apps – they should work normally.
- 📲 Perform system updates over the air to make sure you can receive OTA.
If all the items are met, you can consider the procedure complete. Your Redmi Note 9 Pro is again the same as it came out of the factory. Now the device is protected from accidental flashing by unauthorized persons, and the warranty is formally restored.
💡
Successful shutdown of the bootloader is confirmed by the lack of orange text "unlocked" in Fastboot mode and the possibility of obtaining official OTA-update.