How to flash Xiaomi Redmi Note 4X: official and custom firmware

Xiaomi Redmi Note 4X (codenamed mido) remains a popular smartphone even years after its release. However, over time, official MIUI support is discontinued, and users face slowdowns, bugs or the desire to install the current version of Android.

In this guide, we will look at all the ways of firmware, from official updates through Updater to install custom firmware like LineageOS or Pixel Experience, with special attention to unlocking the bootloader (without it custom firmware can not be installed), preparing drivers and tools, and recovering the device after unsuccessful attempts. If you are a beginner, do not worry: each step is accompanied by screenshots and explanations.

Important: the firmware procedure is always fraught with risks. On the Redmi Note 4X model with a Snapdragon 625 (mido) processor, you can not install firmware from versions with MediaTek - this will lead to a "brick" (inoperability) of the device. Before you start, check the model of your device in Settings → Phone → Model.

1. Firmware Preparation: What to Do Before Starting

Unprepared firmware is like repairing a machine without tools, and to avoid losing data or turning your phone into a brick, follow these steps:

• 📱 Back up. Use the settings. → Additionally. → Backup and reset or applications like Swift Backup (requires root, SMS, Photos and application data.
• 🔋 Charge your phone at least 60%. interruption of the process due to battery discharge can damage system files.
• 💻 Install drivers. For Windows, download Mi Phone Manager from the official Xiaomi website or drivers ADB/Fastboot through SDK Platform Tools by Google.
• 🔗 Download the correct firmware. MIUI Use en.miui.com, for custom forums XDA Developers or 4PDA.

If you're planning to install custom firmware, unlocking the bootloader is a must. Without it, the phone won't let you download the unofficial software. Read the next section on how to do that.

⚠️ Attention: On the Redmi Note 4X lock-down TWRP Trying to do this through fastboot flash will cause the device is locked to fail.

2 Unlock the bootloader on the Redmi Note 4X

Xiaomi is blocking the bootloader on all its devices to protect against unauthorized changes.

1. Get permission from Xiaomi through the Mi Unlock app (you can download it on the official website).
2. Link your Mi Account to your device in Settings → Mi Account → Link your device.
3. Waiting 7-15 days (depending on Xiaomi’s policy) used to take hours, but now the company has tightened the rules.
4. Run Mi Unlock Tool in Fastboot mode (to enter hold Volume down + Power).

Once successfully unlocked, the phone will automatically reset to factory settings. All data will be deleted, so backup in advance.

If the unlock is successful, the bottom of the Fastboot screen will be marked Unlocked, and you can now install custom recovery (TWRP) and firmware.

3. Installation of the official MIUI firmware

The official firmware can be installed in three ways: Updater, Fastboot or Recovery. The first method is the easiest and suitable for updating the current version of MIUI.

Method 1: Update via Updater (without data loss)

1. Download the firmware file with the.zip extension from the MIUI Downloads website.
2. Rename the file to update.zip and move it to the root folder of internal memory.
3. Open Settings → About the phone → System update.
4. Click on the three dots in the upper right corner and select Select the firmware file.
5. Please specify the path to update.zip and confirm the installation.

Method 2: Installation via Fastboot (full reset)

This method is suitable if the phone is not turning on or requires a clean installation.

• 🖥️ Computer with installed ADB/Fastboot.

Instructions:

1. Turn off the phone and press Volume Down + Power to log into the Fastboot.
2. Connect the device to the PC and check the connection command: fastboot devices If the phone is determined, continue.
3. Run the firmware script: fastboot flash all (for Windows) or./flash_all.sh (for Linux/Mac).

⚠️ Attention: If the script flash_all.sh Issue of missing error system.img, use flash_all_except_storage.sh — It stores data in memory, but can lead to bugs.

Connection checked USB (Port 2.0 is more stable than the other port)|The correct version of the firmware is downloaded (for mido)|Antivirus is disabled (it can block fastboot)|Battery charge > 50%|-->

4. Install custom firmware (LineageOS, Pixel Experience, etc.)

Custom firmware gives access to current versions of Android (such as Android 12-14 on the Redmi Note 4X), removes unnecessary Xiaomi apps and improves performance.

• 🔓 Unlocked loader (see section 2).
• 🛠️ Established TWRP Recovery (castomic recovery).
• 📥 Firmware in.zip format and, if necessary, GApps (Google services).

Step 1: Installation of TWRP Recovery

Download the latest version of TWRP for mido from twrp.me.

1. Transfer the phone to Fastboot (Loudness down + Power).
2. Connect to your PC and execute the command: fastboot flash recovery twrp-3.7.0_9-0-mido.img (Replace the file name with the current one).
3. Immediately after firmware, press Volume Up + Power to log into TWRP (otherwise the system will overwrite recovery).

Step 2: Firmware through TWRP

TWRP:

1. Click Wipe → Advanced Wipe and mark Dalvik, Cache, System, Data (full reset).
2. Go back to the main menu and select Install.
3. Specify the path to the firmware file (e.g. lineage-20.0-20260310-mido.zip).
4. Add GApps (if you need Google services) and swipe for confirmation.
5. After installation, press Reboot System.

The first run can take 10-15 minutes. If the phone has been stuck on the logo for longer than 20 minutes, repeat the firmware or check the compatibility of the files.

💡

If after installing custom firmware does not work mobile network, download and run through TWRP patch fix_modem_mido.zip (look 4PDA).

5.Recovery after a failed firmware

If the phone doesn't turn on, freezes on the logo, or shows a No OS installed error, don't panic. In 90% of cases, the device can be restored.

Symptoms and solutions:

If the phone doesn’t respond to buttons at all (full “brick”), try the hardware recovery method:

1. Turn off the battery for 10 minutes (if it is removable).
2. Press Volume Up + Volume Down + Power for 20 seconds.
3. Connect to charging and try to log in to Fastboot.

⚠️ Note: If the phone is heated over 50°C or discharges quickly, this is a sign of kernel incompatibility. Install firmware with another kernel (for example, instead of LineageOS, try Havoc-OS).

6. Post-firmware optimization

Successful firmware is only half the battle, so that the phone is stable.

• ⚡ Turn off unnecessary services. In custom firmware, go to Settings. → Apps and deactivate pre-installed programs (e.g. Mi Browser or Mi Video).
• 🔄 Set up the task scheduler. In LineageOS, turn on Settings. → System system → Extended restart for quick access to recovery.
• 📶 Check the mobile network. If there's no signal, update modem through TWRP (Download a current file for your region).
• 🔋 Calibrate the battery. After the firmware completely discharge and charge the phone 2-3 times for the correct operation of the controller.

To improve productivity:

• Install the FrancoKernel or Perseus kernel (requires root).
• Activate ZRAM in Settings → System → About RAM → Virtual Memory.
• Use Greenify to “freeze” background apps.

💡

After installing custom firmware, be sure to check the work of the sensors (gyroscope, compass, proximity) using the Sensor Test application. If something does not work, file a patch. fix_sensors_mido.zip.

7. Frequent mistakes and how to avoid them

Even experienced users have trouble with firmware, and here are the most common ones:

• 🚫 7-in error TWRP — It means that the firmware is not suitable for your model).
• 🔄 Loaded loading - usually due to lack of a wipe before firmware. Repeat the installation with a full reset.
• 📵 No. IMEI — file persist.img from stock firmware through Fastboot.
• 🔋 Fast battery discharge – calibrate the battery or replace it (the capacity of the original Redmi Note battery) 4X — 4100mAh).

If the root is missing after the firmware (for example, in Magisk), reinstall it:

1. Download the latest version of Magisk (.zip).
2. Put it through TWRP.
3. Reboot the phone.

FAQ: Answers to popular questions