How to reinstall the system on Xiaomi Redmi 4X: 3 working methods + unlock the bootloader

Introduction: When you need to reinstall the system on Redmi 4X

Xiaomi Redmi 4X (codenamed santoni) is still in demand 7 years after its release due to the balance of price and performance. However, over time, users face problems that are solved only by a complete reinstallation of the system: from endless bootloop cycles to critical errors after unsuccessful updates. Unlike new Xiaomi models, where the firmware takes minutes, the Redmi 4X process requires preparation - especially if the bootloader is blocked.

This instruction is relevant for all modifications of Redmi 4X (2/16 GB, 3/32 GB, 4/64 GB) and takes into account the changes of 2026: disabling official MIUI support, the difficulties with unlocking the bootloader through the Mi Unlock Tool, as well as the risks when using custom firmware based on Android 10+. We will consider three methods of reinstallation – from the safest (via Recovery) to radical (ful firmware via Fastboot), and also discuss how to avoid losing IMEI after firmware – a common problem on this device.

Preparation for reinstallation: what to do before the firmware

Unprepared firmware on Redmi 4X leads to one of three outcomes in 80% of cases: a blink (complete failure), loss of network functions (IMEI), or a reboot cycle.

• 🔋 Charge the phone to at least 60% – when discharged during firmware, it will be extremely difficult to restore the device.
• 📱 Make a backup of the data through Mi PC suite TWRP (Cloud backups of Mi Cloud will not be saved SMS, calls and some settings.
• 🔐 Make sure you have a login and password from the Mi Account account linked to the phone. Once the bootloader is unlocked, the device will require authorization.
• 🖥️ Prepare a PC with Windows 7/10/11 (MacOS and Linux may have problems with Qualcomm drivers).

Pay special attention to drivers. Redmi 4X requires:

• 🔧 Qualcomm USB Drivers (for mode) EDL and Fastboot).
• 🔧 Mi USB Driver (Official Driver from Xiaomi for Recognition in Fastboot).

You can download them from the official Xiaomi website ("Tools" section). Install the drivers before connecting the phone to the PC, otherwise the system may determine the device as "unidentified".

Method 1: Reinstall via stock Recovery (without unlocking the bootloader)

This is the safest method, but it only works if:

• ✅ The phone is turned on and loaded into the system (albeit with errors).
• ✅ The bootloader was not changed and the custom Recovery was not installed.
• ✅ You want to get back the stock firmware. MIUI (squirrels cannot be installed this way).

Instructions:

1. Download the official firmware for Redmi 4X from Xiaomi. Select the "Recovery ROM" version (file with.zip extension).
2. Rename the file to update.zip and move it to the root folder of the phone’s internal memory (not to folders!).
3. Turn off the phone. Press Volume up + Power at the same time to enter Recovery.
4. In the Recovery menu, select the language (if available) then:

Wipe Data → Wipe All Data → Confirm


(or “Clear the data → Clear everything → Confirm”)





Install update.zip to System




(or "Install update.zip")

It takes 5-10 minutes. Once completed, the phone will restart automatically. Don't interrupt the process, even if the screen doesn't react for a long time - on the Redmi 4X, the first boot after the firmware can last up to 15 minutes.

Method 2: Fastboot Firmware (with bootloader unlocking)

This method is suitable for:

• 🔄 Recovery of the phone after soft-brick (boot cycle, errors at start).
• 📉 downhreid MIUI (for example, MIUI 12 on MIUI 11).
• 🔓 Install global firmware on the Chinese version of the phone (and vice versa).

Fastboot firmware requires unlocking the bootloader. Since 2026, Xiaomi has tightened the rules: now unlocking requires:

• 📅 Related to Mi Account over 30 days old.
• 📱 The phone must be activated (pass the initial setup).
• 🔗 Stable Internet connection on PC (unlocking occurs through Xiaomi servers).

If the conditions are met, follow the instructions:

1. Download Fastboot ROM for Redmi 4X (file.tgz or.zip and unpack it into a folder without Cyrillic characters (for example, C:\santoni_fastboot).
2. Download the Mi Unlock Tool and install it on PC.
3. Turn on the phone to debug over USB and unlock OEM:

Settings → About Phone → MIUI version (shap 7 times to become a developer)


Settings → Additional → For developers → Debugging by USB (On) + Unlocking OEM (On)

1. Connect your phone to your PC, launch the Mi Unlock Tool, and log in to Mi Account. Follow the unlock program instructions.
2. After unlocking, restart your phone to Fastboot (clip Volume Down + Power).
3. On PC, open the folder with the unpacked firmware and launch the file flash_all.bat (For Windows, wait until the process is complete.

If the firmware is interrupted with an anti-rollback error, you are trying to install an older version of MIUI than the one on your phone.

• Download the latest stable firmware for Redmi 4X (even if it’s newer than your current firmware).
• Repeat the firmware process through Fastboot.

Method 3: Install custom firmware via TWRP (for advanced)

Custom firmware (such as LineageOS, Pixel Experience or Havoc-OS) allows you to upgrade Redmi 4X to Android 10/11, but have a number of limitations:

For custom firmware installation:

1. Unlock the bootloader (see Method 2).
2. Install TWRP Recovery for Redmi 4X (download on the official TWRP website).
3. Download custom firmware (for example, with XDA Developers) and GApps (Google service package if you need them).
4. Reboot your phone to TWRP (clip Volume Up + Power after unlocking the bootloader).
5. In TWRP, do:

Wipe → Advanced Wipe → Tag Dalvik, Cache, System, Data → Swipe to Wipe


Install → Select the firmware file → Swipe to Confirm Flash




(Repeat for GApps if necessary)




Reboot System

Attention, after installing custom firmware:

• 📶 You may have to manually repair it. IMEI Engineer Mode (instruction below).
• 🔒 Some banking applications (Sberbank, Tinkoff) may not work due to the lack of SafetyNet certification.
• 🔄 Updates to firmware will have to be installed manually (no auto updates).

💡

Before installing custom firmware, check it for bugs in the theme on XDA. Pay attention to reviews about camera, GPS and 4G – these modules are often bugged on unofficial firmware for the Redmi 4X.

IMEI recovery after firmware (if the network signal is missing)

One of the most common problems after the Redmi 4X firmware is the loss of IMEI (phone does not catch the network, writes "Emergency Calls Only"), which occurs due to damage to the modem partition or a data reset to the NVRAM. You can restore the IMEI in two ways:

Method 1: Through Engineer Mode (for stock firmware)

1. Open the Phone app and dial ##4636##.
2. Select Phone Information and scroll down to Set preferred network type.
3. If the IMEI is displayed as Null/Null, download the IMEI Repair app (root rights required).
4. Enter the original IMEIs (they are listed on the box or under the battery) and save.

Method 2: Fastboot (if Engineer Mode is not working)

This will require a PC and utility QCN Rebuilder:

1. Download QCN Rebuilder and firmware for your model.
2. Remove the nvitem.bin file from the firmware (usually in the image folder).
3. Open QCN Rebuilder, download nvitem.bin and enter your IMEIs.
4. Generate a new nvitem.bin and run it through Fastboot:

fastboot flash modem NON-HLOS.bin


fastboot erase modemst1




fastboot erase modemst2




fastboot flash fsg fsg.mbn




fastboot reboot

Important! Changing the IMEI incorrectly can lead to permanent network loss. If you're not sure, contact the service center.

💡

If you lose your IMEI after you have firmware, never try to restore it through an application like IMEI Changer without a backup of NVRAM. These applications often replace IMEI with random values, which leads to the IMEI locking in the operator’s database.

Frequent mistakes and their solutions

Even if you follow the instructions correctly, there can be errors on the Redmi 4X, and here are the most common ways to fix them:

If the phone does not react at all after firmware (the indicator does not burn, does not warm up), there may be damage to the loader (hard-brick), in this case, only firmware through EDL (emergency mode) using a Qualcomm box or service center will help.

💡

If the phone reboots cyclically after firmware, try clamping Volume Up + Power for 20 to 30 seconds to reset the cache. Sometimes this helps you exit the bootloop without re-routing the firmware.

FAQ: Answers to Frequent Questions