Xiaomi smartphones are famous for their functionality, but over time, even the most reliable Redmi 9 can require deep software intervention.Reinstalling the operating system is a radical but often the only surefire way to return the device to factory speed, get rid of intrusive viruses or fix bugs after a failed update. Owners often confuse a simple reset with a complete firmware reflash, although these are fundamentally different processes with different consequences for data.
Before you start to take action, you need to clearly understand what kind of recovery method is required in your situation. If the phone turns on and works, but it is glitzy, a standard reset will suffice. However, if the device has gone into an endless reboot or the Recovery menu appears on the screen, you will need to use a computer and special utilities. In any case, preparation takes longer than the installation process itself.
This article covers all the nuances of working with firmware for the Redmi 9 model (codenamed lancelot), we will look at safe methods for ordinary users and more sophisticated options for advanced ones.
Device preparation and data backup
Start by saving important information, as reinstalling Android is guaranteed to delete all user files. Contacts, photos, instant messengers and documents will disappear forever if you don’t back up in advance. Xiaomi owners can use the built-in backup tool or sync with Google Cloud.
To create a local copy, go to the Settings menu. → The phone. → Backup recovery: Here you can select the data to save and specify the path, internal memory or SD-If you're planning a full format, you better copy the reserve to your computer or to the cloud, and remember to also unplug your Mi Account if it's active, so that after flashing it, the theft protection doesn't work.
Make sure the battery is charged at least 60-70%. Interrupting the firmware process due to battery discharge can lead to irreversible consequences, turning the smartphone into a “brick”. USB-cable, preferably original, as cheap analogues often do not withstand long-term transmission of large amounts of data.
- 📱 Charge your smartphone battery to at least 70% for stable operation.
- 💾 Copy all important photos and documents to your computer or cloud.
- 🔑 Remember or write down the password from your Mi Account and Google account.
- 🔌 Find the original. USB-cable or high-quality analogue with thick wires.
⚠️ Note: If your phone has a screen lock (pattern lock, pin code), be sure to remember it. After reinstalling the Android system, you may need to enter data from an account that was previously synced.
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Before starting the procedure, take screenshots of important settings (APN access points, Wi-Fi options) so as not to search for them again on the Internet after resetting.
Standard Reset Method through the Settings Menu
The easiest and safest way to reinstall a system without having to go to a computer is to completely reset the interface, which is fine if the phone turns on, the screen responds to touch, and the menu is stable, and in fact, it's a factory-back, where all the apps and settings are removed, but the firmware version remains current.
To start the process, open Settings and find About Phone. At the bottom of the screen, there will be a Reset button. The system will warn you that all data will be deleted. Once confirmed, the phone will restart and begin the cleanup process, which can take 5 to 15 minutes depending on the amount of information accumulated.
This option is ideal for selling the device or transferring it to another user, as it guarantees the deletion of personal information. However, if the problem was to damage the system files of the OS itself, this method may not help, in which case a deeper intervention through the recovery mode will be required.
☑️ Pre-reset check
Once the reset is complete, the device greets you with the initial setup screen. Don't rush to restore all applications from the backup at once. Give the system a clean run for at least an hour to see if the performance problem has been resolved.
Complete reinstallation via Recovery Mode
If a standard reset is not possible or the system is unstable, Recovery mode is used. This is a separate mini-interface sewn into the phone's memory that allows you to manage boot and memory parts independently of the main Android. To enter this mode on the Redmi 9 turned off, you need to press the power and volume buttons simultaneously.
In the Recovery menu, you can navigate with volume buttons (up/down), and the power button confirms your choice. You need to find Wipe Data and select Wipe All Data. This action will format the user partition completely, and then you can choose Reboot to reboot or Connect with MIAssistant to connect to your PC.
It is important to distinguish between standard Recovery and custom (e.g. TWRP). Xiaomi stock devices have a standard mode that allows you to only reset data or update from a memory card. To install custom firmware requires unlocking the bootloader, which is a separate and more complex procedure.
⚠️ Note: The Wipe All Data item in Recovery does not have a Cancel button. Once you confirm the action, file return will not be possible by any means.
What to do if the Recovery menu is in Chinese?
Using the Mi Flash Tool to flash from PC
For a full-fledged reinstallation of the operating system, for example, to change the region (from China to Global) or recover from serious crashes, the Mi Flash Tool is used on the computer. This method requires an unlocked bootloader if you change the firmware region, but can work without unlocking when restoring the stock version of the same region.
First, you need to download the archive with firmware specifically for the Redmi 9 model (lancelot). The file must have the.tgz extension and be unpacked into the disk root (the path should not contain Cyrillic alphabets or spaces). After connecting the phone in Fastboot mode (clamped down the volume button when turned on), the utility will see the device.
In the Mi Flash Tool, choose the path to unpacked firmware. At the bottom of the window, there are three firmware modes: clean all (complete cleaning), save user data (save data), and clean all and lock (clean and lock the bootloader). For a clean installation, choose the first option. Pressing the Flash button will start a process that takes from 200 to 600 seconds.
| Firmware mode | Data retention | Locking the loader | Risk of error |
|---|---|---|---|
| clean all | No (full reset) | No. | Low. |
| save user data | Yes. | No. | Medium. |
| clean all and lock | No (full reset) | Yes. | High-pitched |
| Fastboot (EDL) | Depends on the account. | Depends. | Very tall. |
* Using the clean all and lock mode on a global firmware device that has Chinese installed, or vice versa, can result in a Hard Brick. Use this mode only if you are flashing the original region.
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Successful firmware through the Mi Flash Tool is possible only with the driver installed ADB/Fastboot and the availability of administrator rights on the PC.
Solving Typical Errors in Installation
When reinstalling Android, users often encounter error codes. For example, the Miss matching image and device error means that the firmware chosen does not match the processor model or bootloader version. For Redmi 9, this is critical, since there are versions with and without different NFC modules, and you can not confuse their files.
If your computer doesn't see your phone in Fastboot mode, the problem is the drivers. Windows Device Manager should display an Android Bootloader Interface. If there's an unknown device with a yellow exclamation point, you need to manually update the driver through the Manager, indicating the path to the driver folder from the Mi Flash Tool.
Another common problem is that the process hangs at a certain percentage (eg, 34% or 99%). USB-You can use a cable or a port. USB 2.0 at the rear of the system unit, avoiding front panels and USB-The antivirus can also block the utility, so it should be temporarily disabled.
- 🔌 Connection error: Replace USB-cable or port, use the original wire.
- 💾 Memory Error: Free up space on the PC system disk for temporary firmware files.
- 🛡️ Antivirus Block: Add Mi Flash Tool to Windows Defender Exceptions.
- 📉 Interrupt process: Do not touch the cable or turn off the PC until complete.
System configuration after reinstallation
After the new version of Android is successfully installed, the initial setup phase begins, and the system will prompt you to select a language, connect to Wi-Fi and log into your Google account. At this point, Redmi 9 may require an update of security components, which is normal.