Xiaomi Mi 3S Firmware Reflash: A Complete Guide from Preparation to Installation

Reflashing Xiaomi Mi 3S is a process that can bring an outdated smartphone to life, improve its performance or install the current version of Android. However, the wrong actions can be fraught with “bricking” the device, so it is important to understand all the nuances. This model, released in 2014, has its own features: a closed bootloader, a specific architecture of the Qualcomm Snapdragon 800 processor and limited support for custom firmware in 2026.

Unlike modern Xiaomi devices, where the upgrade process is highly automated, working with the Mi 3S requires manual intervention. The choice between the official MIUI and custom builds like LineageOS depends on your goals: the first will give stability and support for branded features (for example, IR Blaster), the second – current Android and the lack of redundant software. In this article, we will analyze both options, paying attention to critical points that are often missed even by experienced users.

Preparation for Flashing: What to Do Before Starting

The first and most important step is data backup. The Xiaomi Mi 3S doesn't have a memory card slot, so all photos, contacts and apps are stored in internal memory. Use Mi Cloud (if your account is not blocked) or programs like ADB Backup to create a full copy:

• 📱 Contact and SMS: Export through the Contacts app to the file VCF.
• 📷 Photo/video: copy the folder DCIM PC-only USB-cable MTP).
• 🔑 Wi-Fi Passwords: Save a list of networks with passwords (WiFi Password Viewer app).
• 🎮 Game saves: use cloud-based games (Google Play Games, Mi Account).

Next, check the bootloader version and unlock status. To do this, type ##4636## in the dialer, then go to Phone Information. If the Lock State bar says Locked, the bootloader is locked, you will have to unlock it through the Mi Unlock Tool. Note: Xiaomi may refuse to unlock for devices older than 3 years (as in the case of the Mi 3S), so this step may require circumventing the restrictions.

Unlocking the bootloader: bypassing the restrictions of Xiaomi

The official Mi Unlock Tool often refuses to work with the Mi. 3S Because of an outdated model, the alternative is to use it. EDL-The power download mode, which allows you to flash the device around the locks:

1. USB Type-A - MicroUSB cable (original, undamaged)
2. MiFlash (2017 or 2018 version – newer devices don’t support older devices)
3. Firmware in.tgz format for your model (download only from the official Xiaomi website).
4. Qualcomm HS-USB QDLoader 9008 drivers (installation manually through Device Manager).

To transfer the phone to EDL-Mode, turn it off, then press the Volume Up buttons. + Loudness down + Meals for food 10–15 The screen will remain black, but the PC must define the device as QHUSB_BULK Task Manager. Use of EDL-Xiaomi’s Unauthorized Regime Could Lead to Blocking IMEI — Recovering it later will be very difficult.

Firmware selection: official MIUI vs custom builds

For Xiaomi Mi 3S, there are several types of firmware available, each with pros and cons. Official MIUI builds are divided into:

• 🌍 Global Stable: the most stable version, but with reduced functionality (no themes, some Chinese features).
• 🇨🇳 China Stable: Full Features, but No Google Services (you’ll have to install manually).
• 🧪 Developer: weekly updates but possible bugs (e.g. fast battery drain).

Custom firmware, such as LineageOS 14.1 (Android 7.1) or Resurrection Remix, lets you upgrade to more recent versions of Android, but deprives you of:

• ❌ Support IR Blaster (DU remote).
• ❌ Optimizations for Snapdragon 800 (possible lags in games).
• ❌ Official Security Updates (last from the community released in 2019).

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If you choose custom firmware, check for a fix for offline charging problem – many Mi 3S builds suffer from this bug.

Install firmware through Fastboot: step-by-step instructions

This method is suitable for official firmware MIUI You need to download the file with the firmware (for example, download the bootloader, cancro_global_images_V12.0.2.0.KXDCNXM_20201207.0000.00_5.0_global_4a8d4b5b8a.tgz) And unpack it in a folder without Cyrillic symbols:

Download MiFlash (version 2018)|Install Qualcomm drivers|Unpack the firmware in the root of the C disk:|Turn off the antivirus.|Charge your phone at least 50%-->

1. Transfer the phone to Fastboot mode: turn off the device, then press Volume down + Power until the hare appears in the eardress cap.
2. Connect the Mi 3S to your PC. Android Bootloader Interface should appear in Device Manager.
3. Launch MiFlash, press Select and point the path to the unpacked firmware.
4. At the bottom, select Clean All (Full Cleaning) or Clean All and Lock (Cleaning + Lock bootloader).
5. Press Refresh, your device should appear in the list. Then click Flash.

It takes 5-10 minutes. When it's done, it automatically restarts. The first run can take up to 15 minutes -- don't interrupt it! If the device is stuck on the Mi logo after the firmware is done, try resetting it with Recovery. + Nutrition).

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Clean all and lock mode will lock the bootloader back, only use it if you are sure you will no longer install custom firmware.

Installation of custom firmware through TWRP

Custom firmware requires TWRP Recovery, an alternative recovery menu, download the latest version for Mi 3S (codenamed cancro) from twrp.me.

1. TWRP firmware: fastboot flash recovery twrp-3.2.3-0-cancro.img fastboot boot twrp-3.2.3-0-cancro.img After that, the phone will reboot to TWRP.
2. Firmware installation: B TWRP Choose the Wipe → Advanced Wipe and mark Dalvik, Cache, System, Data. Go back to the main menu, click Install and select downloaded ZIP-Firmware file. additionally, flash GApps (if they are not in the assembly) and Magisk (for root rights).

Once installed, run Wipe Cache/Dalvik and restart. If the firmware doesn't start, check:

• ✅ Version compatibility TWRP Firmware (e.g. LineageOS 14.1 requires a TWRP 3.2.x).
• ✅ Integrity ZIP-File (damaged archives are a common cause of errors).
• ✅ File availability boot.img in the firmware archive (if not, download separately).

Frequent mistakes and their solutions

Even with the correct following of the instructions, problems can arise, and here are the most common ones and ways to fix them:

⚠️ Warning: If after firmware the phone doesn't turn on and don't respond to buttons, don't panic.Plug it into charging for 30 minutes - sometimes the battery drains to a level where the device can't even boot Recovery.

If none of the methods worked, try flashing the device through EDL-file-based prog_emmc_firehose_8974.mbn (for Snapdragon 800). This method requires deep knowledge and is often used in service centers. Incorrect use of firehose files can lead to irreversible damage to eMMC memory.

Optimizing After Firmware: How to Get Productivity Back

After successful firmware installation, the Xiaomi Mi 3S may be slower than expected.

• 🔋 Battery wear: after 5+ Battery capacity drops to 60-70% during the years of operation, causing sudden shutdowns.
• 🗑️ Memory Fragmentation: eMMC drive in Mi 3S It degrades over time, especially with frequent flashing.
• 🤖 Previous Post:Snapdragon 800 not optimized for modern applications.

To improve productivity:

1. Turn off animation: in Settings → About Phone → MIUI version (tap 7 times to turn on Developer Mode), then in For Developers, set Windows Animation = 0.5x.
2. Use lightweight apps: Replace Google Chrome with Bromite or Via Browser.
3. Limit background processes: in Settings → Applications → Autorun, turn off autoboot for unnecessary programs.
4. Sweep through the FrancoKernel kernel (if you have custom firmware) – it is optimized for the Snapdragon 800.

⚠️ Attention: If the phone gets too hot after firmware, check the thermally conductive paste between the processor and the body. 3S It often dries up after 5-7 years, which leads to overheating and trottling (resetting frequencies).

FAQ: Answers to popular questions