How to block the bootloader on Xiaomi Redmi Note 3: official and alternative methods

The bootloader on Xiaomi smartphones is a software component that controls the boot process of the operating system. On the Redmi Note 3 (codenamed kenzo for the Snapdragon 650 version and kate for MediaTek Helio X10), it is initially blocked by the manufacturer. However, many users will unlock it to install custom firmware or obtain root rights. If you need to return the factory state - for example, to sell the device, warranty repair or restore security - you will have to block the bootloader again.

The process of locking the bootloader on the Redmi Note 3 is officially supported by Xiaomi through the Mi Unlock Tool utility, but has a number of nuances. Unlike unlocking, which requires a Mi Account to be tied and waiting 72-720 hours, blocking usually goes faster. However, improper actions can lead to a “brick” (inoperability) of the device. In this article, we will discuss the official method, alternative ways for power users, as well as the risks and consequences of the procedure.

If you have previously installed custom recavators (such as TWRP) or modified software, you must return the stock firmware before blocking the bootloader. Otherwise, the device may stop booting. Also note that after blocking all data on the phone will be erased - back up important files.

📊 Why would you want to block the bootloader on Redmi Note 3?

Preparation for sale

Restoration of the guarantee

Resolving errors after firmware

Experiment

Other

1. Preparation of the device for locking the loader

Before starting the procedure, make sure your Redmi Note 3 meets the following requirements:

📱 Device model: kenzo (Snapdragon) or kate (MediaTek). Check in Settings → About Phone → Model.
🔄 Version MIUI: Official stock firmware (not custom). If you have a modified version installed, restore the stockware first.
🔋 Battery charge: at least 60%. Interrupting the process due to discharge can lead to irreparable errors.
🖥️ Computer: Windows 7/10/11 (for Mi Unlock Tool), with antivirus and Xiaomi drivers disabled.

Pay special attention to the firmware version. If you installed TWRP or custom core, return the original Recovery through Fastboot:

fastboot flash recovery stock_recovery.img

Where stock_recovery.img is a stock recover file for your model (you can download from the official Xiaomi website or forums like XDA Developers).

Important: If the device has OEM Unlock activated in the developer settings, it must be disabled before blocking, otherwise the process may end in error.

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Before locking the bootloader, check the device's IMEI (type *#06#).If it's missing or incorrect, restore it first through the engineering menu or service center.

2.Official method: lock via Mi Unlock Tool

Xiaomi provides the official Mi Unlock Tool for unlocking and locking the bootloader, but for Redmi Note 3, the process has features:

Download Mi Unlock Tool from the official website (version no lower than 5.5.228.30).
Log in to the Mi Account that was previously used to unlock.
Connect your phone in Fastboot mode (clip Volume Down + Power when the device is off).
Select the “Lock” option in the utility and follow the instructions.

Unlike unlocking, locking usually takes place without a long wait, but the utility can give out errors:

❌ Couldn't lock - the device does not support locking via the Mi Unlock Tool (relevant to older firmware versions).
❌ Account not bound — Mi Account is not tied to the device. You must log in to Settings → Mi Account.
❌ Device not supported — Redmi Note 3 model is not recognized. Try updating the utility or using an alternative method.

If the process is successful, the phone will automatically restart and reset to factory settings, and once the bootloader is locked, custom firmware or recovery will be impossible to install without re-unlocking.

Install official firmware | Disable OEM Unlock | Charge phone >60% | Download Mi Unlock Tool |Authorize in Mi-account-->

3. Alternative methods of blocking the loader

If the Mi Unlock Tool doesn’t work (for example, due to a Couldn’t lock error), you can use Fastboot commands.This method requires experience with ADB/Fastboot and is only suitable for users who understand the risks.

Instructions for the Snapdragon version (kenzo):

Download Google’s Platform Tools and unpack the archive.
Connect your phone in Fastboot mode.
The command is: fastboot oem lock
Confirm the action on the phone screen (if you receive a request).

For MediaTek, the process is more complicated because of the chipset.

Download stock firmware in.tgz format for your model.
Use the SP Flash Tool for full flashing with the Lock Bootloader tick.

Warning: On MediaTek devices, the wrong firmware can lead to hard-brick (complete failure without recovery via Fastboot).If you are not sure about your actions, contact the service center.

What if the phone doesn’t turn on after locking?

If the device does not respond to the power button, try: 1. Press Volume Up + Power for 10-15 seconds (forced reboot). 2. Connect to charge for 30 minutes, then try to turn on again. 3. If the screen remains black, you will need to flash through EDL- mode (only for power users or service centers).

Possible errors and their solutions

The process of blocking the bootloader can be accompanied by errors, the following are the most common of them and ways to fix them:

Mistake.	Reason.	Decision
Invalid device state	The device is in an unstable state (for example, a custom recaveri is installed).	Return the stock recavator and firmware, then try again.
Mi account not logged in	The phone does not have an authorized Mi Account used to unlock.	Log in to Settings → Mi Account and link the device.
Device is locked. Cannot lock again	The bootloader is already blocked (or the process has been interrupted previously).	Complete reset via Fastboot: fastboot erase userdata.
Remote: oem lock is not allowed	Xiaomi has blocked the possibility of blocking for this model/region.	Use alternative methods or contact a service center.

If none of the methods worked, check:

🔌 Cable USB: Use the original Xiaomi cable (cheap analogues can cause data transmission errors).
🖥️ Ports USB: Connect to the rear ports of the system unit (laptops may have power issues).
🔄 Driver Version: Update Qualcomm drivers (for kenzo) or MediaTek drivers (for kate) through Device Manager.

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If the phone loads in Fastboot mode with an Invalid BL Lock State error after locking, then the firmware does not match the bootloader version. The solution is to flash the stock version of MIUI through MiFlash with the clean all and lock option.

5. Consequences of blocking the loader

Locking the bootloader returns the Redmi Note 3 to a “out of the box” state, but has several important consequences:

Pros:

✅ Warranty service: The device is once again compliant with Xiaomi service centers.
✅ Security: Closed attack vectors via modified software (e.g. root exploits).
✅ Stability: no conflicts between custom modules and the system.

Cons:

❌ Loss of functionality: It is not possible to install Magisk, Xposed or custom cores.
❌ Firmware restrictions: Updates MIUI will only be installed through official channels.
❌ Data Reset: All user files, settings and applications will be deleted.

If you block the bootloader to sell the device, be sure to do:

Reset via Settings → Additional → Recovery and Reset.
Unleash your Mi Account (otherwise, the new owner will not be able to activate the phone).
Check the operability of all modules (camera, sensors, communication).

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Once the bootloader is blocked, it is recommended to update the firmware to the latest stable version of MIUI via Settings → System Update.This will eliminate possible bugs associated with version incompatibility.

6.How to return an unlocked bootloader after blocking

If you change your mind and want to unlock the bootloader again, the procedure will be standard:

Link the Mi Account to the device.
Wait 72-720 hours (depending on Xiaomi policy).
Use the Mi Unlock Tool to unlock.

But keep in mind:

🔄 Waiting: After locking, the unlock timer is reset.
📱 Limitations: On some firmware, Xiaomi blocks the ability to re-unblock for devices older than 3-4 years.
⚠️ Risks: Frequent changes in the bootloader state can lead to software failures.

There are workarounds for the Redmi Note 3 (kenzo/kate) (e.g., via EDL- mode), but they require special hardware (Deep Flash Cable) and knowledge.

Can I unlock the bootloader without waiting?

Theoretically, yes, but only through informal methods (e.g. exploit for older versions of MIUI).However, this violates Xiaomi's rules and can lead to account or device locking. Risks: - Loss of warranty. - "Soft-brick" (cyclical reboot). - IMEI lock (for versions with MediaTek).

7.Restoring stock firmware before locking

If your Redmi Note 3 has custom firmware installed (for example, LineageOS, Pixel Experience), before blocking the bootloader, you need to return the official software.

For Snapdragon (kenzo):

Download the stock firmware in.tgz format from the MIUI Download website.
Unpack the archive and launch MiFlash.
Connect your phone in Fastboot mode and select the clean all option.
Press Flash and wait until it is completed (the process will take 5-10 minutes).

For MediaTek (kate):

Use the SP Flash Tool with the scatter.txt file from stock firmware.
Select Firmware Upgrade (not Format All + Download to avoid erasing IMEI!).
Connect the phone to the switched off (drivers must be installed in advance).

After the firmware check:

📶 IMEI: dial *#06# and the original number should be displayed.
🔄 Load: The phone should be on normally and undergo initial setup.
🔒 bootloader status: The Fastboot must display the word Locked.

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If the phone doesn't detect the SIM- card after the firmware, it means that the modem partition (relevant to MediaTek) has been erased, so the solution is to flash only modem again through the SP Flash Tool.

FAQ: Frequent questions about bootloader lockdown

❓ Can I block the bootloader without losing data?

No. Locking the bootloader is always accompanied by a full reset. It is recommended to back up in advance through Settings → Additional → Backup or third-party utilities like Titanium Backup (requires root).

❓ Why can't Mi Unlock Tool see my device?

The reasons may be: Xiaomi drivers are not installed (download Mi Phone Manager); the phone is connected in MTK Preloader mode instead of Fastboot (relevant to kate); the Mi Unlock Tool version is outdated (update to the latest).

❓ What if, after locking, the phone asks for a password from an old Mi Account?

This means that the device has remained tied to the previous account, solutions: Enter the old account (if you remember), if the account is deleted, contact Xiaomi with proof of ownership (check, box), and you will need an authorized service center to reset the link through the EDL.

❓ Can I lock the bootloader on the Redmi Note 3 with a damaged screen?

Technically, but only if: The phone is detected by the computer in Fastboot mode. You can confirm actions via ADB (e.g., adb reboot bootloader command). If the screen is completely black and there is no connection reaction, locking is impossible without repairing the display.

❓ Does bootloader Block Remove Root Rights?

Yes, locking the bootloader automatically removes root, Magisk, Xposed, and other system modifications, and if you need root rights again, you'll have to re-unblock the bootloader and install Magisk again.

If your question is not covered in the FAQ, check the official resources of Xiaomi or contact thematic forums such as XDA Developers (section Redmi Note 3). Remember that any manipulation with the bootloader you perform at your own risk!

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Before selling Redmi Note 3 with a locked bootloader, run fastboot oem device-info — the answer should be Device unlocked: false.