Step-by-step: How to flash Poco X3 NFC through Fastboot without errors

Xiaomi Poco X3 NFC remains one of the most popular smartphones among custom firmware enthusiasts due to its balance of price, performance and community support. However, firmware through Fastboot is a process that requires accuracy: one mistake can turn a device into a brick. This article will help avoid the typical problems, from unlocking the bootloader to choosing the right version of MIUI or custom ROM.

Unlike firmware through Recovery, Fastboot allows you to install official or unofficial software even on locked devices (provided the bootloader is unlocked), and we will cover all the steps from preparing drivers to solving errors like anti-rollback or invalid sparse file. We will pay special attention to the nuances of Poco X3 NFC (codename surya, which is often overlooked in universal guides.

1. Firmware Preparation: What to Do Before Starting

Before you start firmware, make sure all the prerequisites are met. Fastboot erases all data on the device, including internal memory (including photos in the DCIM folder and files in Download).

List of mandatory actions:

• 📱 Backup your data via Mi Cloud, Google Drive, or locally on your PC (use Xiaomi Backup or Titanium Backup for root users).
• 🔋 Charge your smartphone to at least 60% – with a low charge, the Fastboot can interrupt the process.
• 💻 Install it on an Android PC SDK Platform-Tools (or separately fastboot and adb).
• 🔌 Prepare quality. USB-cable (preferably original from Xiaomi) as cheap cables can cause data transmission errors.

Also check the current version of MIUI in settings (Settings → About Phone → MIUI Version) to avoid problems with anti-rollback, a security mechanism that blocks rollbacks on older firmware versions. For example, if your device is on MIUI 14, the firmware of MIUI 12.5 may block the bootloader.

2 Unlocking the bootloader: a mandatory step before the firmware

Xiaomi Poco X3 NFC has a locked bootloader by default. Without it, firmware via Fastboot is impossible. The process requires linking the Mi Account to the device and waiting for confirmation from Xiaomi servers (usually 72-168 hours).

Instructions for unlocking:

1. Activate Developer Options: Go to Settings → About Phone and click on MIUI 7 times.
2. Enable USB Debugging and OEM Unlocking in Settings → More → For Developers.
3. Download the Mi Unlock Tool and log in to your Mi Account.
4. Connect your phone in Fastboot mode (press Power + Volume down when the device is off) and follow the program instructions.

⚠️ Note: If you previously unlocked the bootloader on another Xiaomi device, it can take up to 30 days to link your account, and Mi Unlock Tool sometimes gives you a “Couldn’t unlock” error – in this case, try using a different version of the utility (for example, 6.5.224.24 instead of the last one).

Once successfully unlocked, the device will automatically reset to factory settings. Now you can start the firmware.

Linked to Mi Account device | USB | Installed Fastboot | Drivers Installed Smartphone Charged Over 50% | Downloaded Mi Unlock Tool-->

3. firmware choice: official MIUI vs custom ROM

There are two types of firmware available for Poco X3 NFC (surya):

1. Official (from Xiaomi): stable and weekly versions of MIUI are recommended for most users, as they are tested for compatibility with iron.
2. Custom (from the community): LineageOS, Pixel Experience, ArrowOS, and others. Offer pure Android without branded MIUI bells and whistles, but may have bugs (such as a broken NFC or camera).

Where to download:

• 🔗 Official firmware: MIUI Downloads (select the version for surya).
• 🔗 Castomy ROM: XDA Developers or Telegram chats.

For beginners, we recommend starting with the official MIUI. If you want custom firmware, pay attention to the Android version: the Poco X3 NFC officially supports up to Android 12, but unofficial Android 13/14 ports can work with restrictions.

4. Install firmware via Fastboot: step-by-step instructions

When the firmware is downloaded and the bootloader is unlocked, you can start installing. For official MIUI, use the Mi Flash Tool, for custom ones, use fastboot commands manually.

Instructions for the official MIUI:

1. Unpack the downloaded archive with firmware (should be a file) flash_all.bat or flash_all.sh).
2. Connect your phone in Fastboot mode (clip Power + Volume down).
3. Launch the Mi Flash Tool, select the firmware folder and press Refresh (the device must be determined).
4. Select Clean All or Clean All and Lock (if you want to lock the bootloader after you have been firmware).
5. Press Flash and wait until it is completed (usually 5-10 minutes).

Instructions for custom firmware:

1. Unpack the archive with the firmware in the folder with fastboot and adb.
2. Open the command prompt in this folder (Shift + PCM → Open the PowerShell window here).
3. Type commands in turn: fastboot flash boot.img fastboot flash dtbo dtbo.img fastboot flash system.img fastboot flash vendor.img fastboot flash recovery.img fastboot reboot

⚠️ Note: If the firmware requires additional steps (such as firmware or modem firmware), these must be done before the device restarts. Otherwise, the smartphone may not boot or lose communication.

Once the firmware is successful, it can take up to 15 minutes to turn on the first one, which is normal. Don't interrupt the process!

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If the Mi Flash Tool gives an error "critical partition flashing is not allowed", try using an older version of the utility (for example, 2018.5.4.0) or manually run the firmware through fastboot commands.

5. Typical errors and their solution

Even if you follow the instructions accurately, you can get errors.

If the device stops turning on (brick), try:

1. Press Power + Volume up for 20-30 seconds (sometimes helps with a soft brique).
2. Switch MIUI to the Mi Flash Tool in Clean All mode.
3. Use it. EDL-Mode (requires an authorized Xiaomi account and Qualcomm boxing).

In 90% of cases, the device can be repaired, but if the bootloader is damaged at the eMMC level, repairs may be required at the service center.

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If the sensor, Wi-Fi or camera is not working after the firmware is installed, chances are you have installed firmware for another model (for example, for the Poco X3 Pro instead of the Poco X3 NFC).

6. Additional settings after firmware

After successful firmware, it is recommended to follow several steps to optimize the operation of the device:

• 🔄 Make reset to factory settings (Settings) → Additionally. → Resetting settings, even if the firmware was clean, will eliminate possible conflicts.
• 🔒 If you have installed custom firmware, check SafetyNet status (via Magisk or SafetyNet Test.
• 📡 Update firmware and modem to the latest version (relevant to custom firmware) to improve communication stability and camera performance.
• 🔋 Calibrate the battery: fully discharge and charge the device 2-3 times in a row.

For custom firmware, it is also useful:

• Install Magisk to obtain root rights (if required).
• Set up a kernel auditor to optimize performance.
• Disable unnecessary Google services (if the firmware is without GApps).

If there are bugs after firmware (such as spontaneous reboots), check logs via adb logcat or contact the XDA forum describing the problem.

7. How to return the official firmware with custom

If custom firmware was unstable or you want to return the warranty, you can backstitch the official MIUI. The process is almost identical to the original firmware, but there are nuances:

1. Download the full official firmware (not Recovery, but Fastboot).
2. Unpack the archive and delete the file flash_all_lock.bat (If you do not want to block the loader).
3. Sweat through the Mi Flash Tool in Clean All mode.
4. If the bootloader has been locked, unlock it again (see Section 2).

⚠️ Note: When returning to the official firmware after custom, an anti-rollback may work if the version MIUI In this case, first run the intermediate version (for example, MIUI 13 before MIUI 14).

After returning to the official firmware, all data will be erased, and root rights and Magisk will be deleted.

FAQ: Frequent questions about Poco X3 NFC firmware