Reflashing Xiaomi Redmi 3S via Fastboot: a complete guide with unlocking the bootloader

Xiaomi Redmi 3S

land

Global ROM

custom-assembly

Android One

Fastboot

In this article, you will find a step-by-step guide to all the nuances of the Redmi 3S, including solving typical errors like anti-rollback, driver problems or a “brick” after a failed firmware. We will discuss how to avoid data loss, what tools to use (Mi Flash Tool, ADB/Fastboot), and why some firmware may not be suitable for your version of the device. If you have never flashed a Xiaomi smartphone before, don’t worry: the manual is adapted for beginners, but with technical details for experienced users.

Before you start, consider that flashing through Fastboot is not just an airburst update; it is a complete rewriting of the system partition that can both revive your Redmi 3S and turn it into a brick if you skip critical steps. For example, devices with a locked bootloader will not accept custom firmware without first unlocking through the official Xiaomi service, and trying to sew a newer version of MIUI into the old one without considering the anti-rollback will lead to the inability of the phone.

In this article, we'll focus on official firmware (stable/beta) and legal unlock methods. If you're looking for custom ROMs like LineageOS or Pixel Experience, after reading this, you'll need to learn more about TWRP installation and ADB Sideload, but first, let's get to the basics.

1. Firmware Preparation: What You Need to Know Before Starting

Fastboot flashing is not a process that can be started on the knee, and lack of training can lead to data loss, software failures, or hardware problems, and here are the key points to consider before connecting your phone to your computer:

First, determine the current version of MIUI and the bootloader status. Go to Settings → About Phone → MIUI Version. Write down the full build number (e.g. V12.5.3.0.RALMIXM). Also check if the bootloader is unlocked: turn off the phone, press Volume down + Power, and if you see Unlocked, you can skip the unlock step. If not, you will have to get permission from Xiaomi.

Second, back up all the data. Fastboot's firmware formats the internal memory, so:

• 📱 Back up your contacts through Google Account or export them to.vcf.
• 📸 Transfer photos and videos to your computer or the cloud (Google Photos, Mi Cloud).
• 🔑 Save it. SMS and call logs using apps like SMS Backup & Restore.
• 🎮 If you play device-based games, check if they support keeping progress in the cloud.

Third, make sure you have all the tools you need:

• 🖥️ Computer running Windows 7/10/11 (Mi Flash Tool is best avoided macOS/Linux because of driver problems).
• 🔌 Original. USB-cable (cheap cables can cause data transmission errors).
• 🔋 Battery charge of at least 60% (firmware can take up to 15-20 minutes).
• 🛠️ Programs: Mi Flash Tool, ADB/Fastboot, Qualcomm drivers.

⚠️ Attention: If your Redmi is 3S It was bought in China and works for China. ROM, after Global's firmware ROM Google’s Play Market Services may be terminated, GMS). This will require additional Google Installer installation or manual GApps stitching.

2 Unlocking the bootloader: a mandatory step for firmware

The bootloader on all Xiaomi smartphones is locked by default, a security measure that prevents unofficial software from being installed. To flash Redmi 3S through Fastboot, it must be unlocked. The process takes up to 72 hours (due to Xiaomi's verification) and requires the Mi Account to be linked to the device.

Here's the step-by-step instruction:

1. Link your Mi Account to your phone: go to Settings → Xiaomi Account and log in.
2. Activate USB debugging: go to Settings → About Phone, tap 7 times on the MIUI Version, then go back to Settings → Additional → For Developers and turn on USB Debugging.
3. Download the official unlock utility (Mi Unlock Tool) and install it on your computer.
4. Connect your phone to your PC in Fastboot mode (turn off the device, press Volume Down + Power).
5. Launch the Mi Unlock Tool, log in to the same Mi Account as on your phone, and follow the program instructions.

After sending a request to unlock Xiaomi will send a status notification (usually in 1-3 days).Do not try to unlock the bootloader through informal tools, this can lead to the blocking of the account or the “brick” of the device.

⚠️ Note: If you are buying a Redmi 3S "hand, make sure the previous owner untie his Mi Account from the device, otherwise unlocking will not be possible without his data.

After successfully unlocking your phone in Fastboot mode, you'll see the words Unlocked. Now you can start choosing the firmware.

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If the Mi Unlock Tool is running a "Couldn't verify device" error, try using a different version of the program (e.g. 5.5.223.24 instead of the last one) or connect your phone to another version. USB-port (preferably 2.0).

3. firmware selection: which version of MIUI to install on Redmi 3S

There are several types of firmware available for Xiaomi Redmi 3S (model land), and the choice depends on your goals:

• 🌍 Global Stable – official firmware with support for Google Services, suitable for most users.
• 🇨🇳 China Stable is a Chinese version without Google services, but with more frequent updates.
• 🧪 Beta – test builds with new features but possible bugs.
• 🔧 Fastboot ROM — Complete firmware package via Mi Flash Tool (extension.tgz).
• 📱 Recovery ROM — for installation through stock recovery (extension.zip).

To firmware through Fastboot, you need a file with the extension.tgz. You can download it on official resources:

• The official MIUI website (select the Redmi 3S/3X model).
• Xiaomi Firmware Updater (alternative source with archive of old versions)

Note the firmware version of Android. Redmi 3S originally ran on Android 6.0 Marshmallow, but later received updates to Android 7.1 Nougat. Installing firmware on a newer version of Android (such as Android 8+) will result in an anti-rollback error and a “brick.”

If you plan to install custom firmware (like LineageOS 14.1), first run the official Global Stable through Fastboot, and then install TWRP and custom.

4.Installation of drivers and Mi Flash Tool: PC setup

To run through Fastboot, the computer must recognize Redmi 3S in bootloader mode. Without the right drivers, the Mi Flash Tool won't see the device, and the process will end in error.

First, download and install:

• 🖥️ Mi Flash Tool (last version).
• 🔧 ADB and Fastboot (part of Android) SDK Platform-Tools).
• 🔌 Qualcomm drivers (if Windows does not recognize the device in Fastboot).

To install drivers manually:

1. Connect your phone in Fastboot mode (clip Volume Down + Power).
2. Open Device Manager on PC, find a device with an exclamation point (usually Android or Qualcomm HS-USB QDLoader 9008).
3. Right-click → Update the driver → Search on this computer → specify the folder with Qualcomm drivers.

After installing the drivers, check the connection:

1. Open the command line (Win + R → enter cmd).
2. If the device is recognized, you will see its serial number (for example, 1234567890abcdef fastboot).

⚠️ Note: If the fastboot device command does not show the device but the drivers are installed, try: Use another USB-cable (original from Xiaomi) Connect your phone to the port USB 2.0 (blue ports) USB 3.0 may not work. Disable driver signatures in Windows (via Run) → gpedit.msc).

Install the Mi Flash Tool|Download ADB/Fastboot|Install Qualcomm drivers|Check the connection via fastboot devices|Download the firmware.tgz for Redmi 3S-->

5. Xiaomi Redmi 3S firmware via Fastboot: step-by-step instructions

Now that you're done, you can start the firmware, and it'll take 10 to 20 minutes, but you can't interrupt it.

Step. 1. Unpack the downloaded firmware.tgz in a folder without Cyrillic characters (for example, C:\MIUI\land_global). There's gotta be a file inside. flash_all.bat.

Step 2. Launch the Mi Flash Tool on behalf of the administrator. In the upper right corner, select Select and specify the folder with the unpacked firmware.

Step 3: Connect Redmi 3S in Fastboot mode (Put Volume Down + Power) The device must be determined in the program (the serial number will appear).

Step 4. At the bottom of the Mi Flash Tool, select the firmware mode:

• Clean all – complete cleaning (recommended for changing the firmware region, for example, from China to Global).
• Clean all and lock – clean + lock the bootloader (use if you want to return the stock firmware and lock the bootloader).
• Save user data – saving user data (not recommended, may cause failures).

Step 5: Press Flash and wait until the process is complete. The log should have green success lines. The phone will automatically reboot.

If the firmware ended in error, check:

• 🔌 Cable and port USB (Try another cable).
• 📁 The path to firmware (should not be Cyrillic or gaps).
• 🔄 Mi Flash Tool (sometimes helps to roll back to an older version).

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If after firmware the phone hung on the Mi logo for more than 10 minutes, reset via Recovery (click Volume up + Power, select Wipe Data).

Typical errors and their solution

Even with the instructions followed accurately, errors can occur, and here are the most common problems when running Redmi 3S firmware via Fastboot and how to fix them:

If Redmi 3S does not boot or restarts cyclically after firmware:

1. Try flashing another version of MIUI (for example, take China instead of Global).
2. Recovery is done through Recovery (Wipe Data).
3. Check if the anti-rollback worked (if so, go through a newer firmware).

If the Mi Flash Tool is 0x80070002 or 0xc0000005, it is usually due to:

• 🛠️ Incompatible version of Windows (try Windows 10) x64).
• 🔌 Antivirus conflict (disable Windows Defender or Avast while you are firmware).
• 📂 By way of firmware with gaps or Cyrillic alphabet.

7. After firmware: setup and optimization

After a successful firmware Redmi 3S will require initial configuration.

Initial setting:

• 🌐 Select a language, region and connect to Wi-Fi.
• 🔑 Sign in to Google account (if you have logged in to Global) ROM).
• 🔄 Restore data from backup (contacts, SMS, photo).

Checking the working capacity:

• 📞 Make sure calls and mobile network are working (check settings) APN operator).
• 📶 Check Wi-Fi, Bluetooth and GPS.
• 🔋 Calibrate the battery: discharge the phone to 0%, then charge to 100% without interruptions.

3. Performance optimization:

• 🚀 Turn off animations: go to Settings → Additionally. → For developers and install Windows animation = 0.5x.
• 🗑️ Clear the cache: Settings → Memory. → Clear the cache.
• 🔒 Turn off unnecessary background processes: Settings → Annexes → Auto-start.

If you have flashed China ROM and need Google services, install Google Installer from APKPure or run GApps through TWRP.

⚠️ Note: After the Global Firmware ROM On a previously blocked bootloader, some features (such as Mi Pay or Game Turbo) may not work properly.

FAQ: Frequent questions about Redmi firmware 3S