Xiaomi Redmi 9 is one of the most popular budget smartphones, but even it is not immune to system failures. If your device suddenly stopped responding to touch, hangs on the screensaver of MIUI or slows down in simple applications, do not rush to carry it to the service center. In 80% of cases, you can solve the problem yourself in 10 to 30 minutes.
In this article, we will look at all possible causes of freezes, from overloaded memory to hardware malfunctions, and give step-by-step instructions for restoring health, and pay special attention to the hidden developer settings that help diagnose a problem without root rights.
First, determine how the hanging occurs:
- 📱 Full freeze: screen does not respond, buttons do not work.
- 🔄 Cyclical reboot – the phone turns on, shows the Redmi logo and shuts off again.
- 🐢 Lags in the interface – slow scrolling, delays when opening applications.
- 🎮 Hanging out in games - flies out PUBG Mobile, Genshin Impact or other heavy-duty applications.
If the smartphone responds to pressing, but is slow — the problem is more software. If it does not turn on at all or goes into an endless reboot — hardware malfunctions (for example, a memory chip dump) are possible.
1. Forced reset - the first step when getting stuck
If the Redmi 9 is completely frozen and does not respond to touch, try a hardware reset, which works even in critical system failures.
For forced reboot:
- Press the power button for 10-15 seconds.
- If it doesn’t work, press the power + Volume up for 20 seconds at the same time.
- After the vibration and the MIUI logo appears, release the buttons.
If the smartphone is turned on, the problem is temporary (for example, Conflict with the background application). If you are again stuck on the logo, move to the next section.
⚠️ Note: Do not use this method more than 1 time per day. Frequent forced reboots can damage the file system, especially if the freeze is associated with disk write errors.
2. Clearing the cache and data of problematic applications
Most often, Redmi 9 starts to slow down due to overcrowded cache or conflicts between apps. For example, Facebook, Instagram or TikTok can take up to 5-10 GB of temporary files, which leads to lags.
How to clear the cache:
- Go to Settings → Applications → Application Management.
- Choose an app that crashes frequently (like YouTube or Chrome).
- Press Warehouse. → Clear the cache.
- If the lags continue, click Clear Data (Warning: This will delete all app settings!).
| Annex | Average cache size | Frequent cause of lags |
|---|---|---|
| 3-8 GB | Background synchronization and autoplay video | |
| 1-4 GB | Caching stories and reels | |
| Google Play Services | 500 MB-2 GB | Conflicts with system updates |
| MIUI Launcher | 200-500 MB | Mistakes of animation rendering |
If you don’t know which app is to blame, clear the cache of all apps at once:
- Go to Settings → Storage → Clean.
- Select the Cache Data and confirm the cleanup.
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After cleaning the cache, restart the phone. The first turn on can take up to 5 minutes - this is normal, the system recovers temporary files.
3. Checking the free space on the internal storage device
Redmi 9 is equipped with eMMC 5.1 drive, which is very slow when filling up more than 85%.If you have less than 3-4 GB of free space, the system starts to fail even for simple tasks (for example, when opening WhatsApp or Telegram).
How to make room:
- 📁 Delete unnecessary photos and videos (use Gallery) → Recycle Bin for Recovering Accidentally Deleted Files).
- 🎵 Transfer music to a memory card (if installed).
- 📱 Remove unused applications through Settings → Annexes.
- 🗑️ Clean the Download folder (it often accumulates outdated ones) APK-file).
To check the vacant space:
- Open the settings → About the phone → Storage.
- If the partition is more than 15 GB, this is a sign of firmware errors (see Section 6).
Delete duplicates photo|Transfer files to memory card |Clear app cache |Delete unused APK|Disable auto download in instant messengers-->
⚠️ Note: Do not use cleaners like Clean Master or CCleaner. They often delete important system files and can exacerbate the problem.
4. Disabling animations and speeding up the interface
If Redmi 9 slows down when scrolling menus or opening apps, hardware limitations on the Helio G80 processor may be to blame.Switching off animations reduces the load on the GPU and speeds up work by 20-30%.
How to turn off animations:
- Activate Developer Mode: Go to Settings → About Phone and click on MIUI Version 7 times.
- Back to Settings → Additionally. → For developers.
- Find the items: Window animation scale → Turn off animation scale transition → Turn off animation duration of animation → Turn off
It is also recommended that:
- 🔄 Disable Auto-Update Apps in Google Play.
- 📱 Install a light theme (for example, Light instead of Dark).
- 🔋 Enable Battery Mode in Settings → Battery (limits background activity).
Why is MIUI 12/13 on Redmi 9 slowing down?
5. Reset to factory settings (Hard Reset)
If the previous methods didn't work, and the phone still freezes, it's a complete reset, which will delete all the data, but it will return the system to its original state.
How to reset Redmi 9:
- Go to Settings → About the phone → Reset settings.
- Choose to erase all data.
- Enter the password (if set) and confirm the reset.
If the phone is not switched on:
- Press Power + Volume Up before the Fastboot logo appears.
- Select Recovery Mode (volume buttons).
- From the recovery menu, select Wipe Data → Wipe All Data.
⚠️ Warning: After resetting the first 10 to 15 minutes, the phone may brake, which is normal, the system indexes files!
6. Flashing through Fastboot (for power users)
If Redmi 9 is stuck on the logo or goes to the bootloop, the cause may be a damaged firmware, in which case reinstalling MIUI via Fastboot will help.
What you need:
- 🖥️ Windows computer 10/11.
- 🔌 Cable USB (preferably original).
- 📥 Firmware for Redmi 9 (codenamed Lancelot) from Xiaomi Firmware.
- 🛠️ The Mi Flash Tool.
Step-by-step:
- Download and unpack the firmware into a folder without Cyrillic characters (for example, C:\MIUI\lancelot).
- Install the Mi Flash Tool and Xiaomi USB drivers.
- Turn off the phone and press Power + Volume Down to log into Fastboot.
- Connect your smartphone to your PC and in the Mi Flash Tool, select a folder with firmware.
- Press Refresh, then Flash (select Clean All for full cleanup).
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Fastboot flashing removes all data, including photos in internal memory. If the phone is not detected by the computer, check the cable or try another one. USB-port (preferably) USB 2.0).
7. Diagnostics of hardware malfunctions
If Redmi 9 freezes even after flashing, the problem may be in the hardware:
- 🔋 Faulty battery – if the phone turns off at 30-40% charge or overheats.
- 🧠 Memory chip dump – frequent reboots, file read errors.
- 🔌 Display plume problems - screen flickers before hanging.
- 📡 Faulty module Wi-Fi/Bluetooth — The phone freezes when connected to the network.
How to check the hardware components:
- Run ##4636### in the dialer and select Testing (check sensor, speakers, camera).
- Install the AIDA64 app and check the processor temperature (normal: up to 60°C in idle).
- See error logs through Settings → About phone → Error report.
Typical symptoms of hardware problems:
| Symptoms. | Possible cause | Decision |
|---|---|---|
| Freeze when charging | Faulty power controller | Replacement of battery or board |
| Artifacts on the screen before hanging | Graphics chip dump | Solding a chip or replacing a motherboard |
| The phone doesn't turn on after falling | A plume break or a crack on the board | Diagnostics at the service center |
⚠️ Warning: If Redmi 9 freezes due to overheating (temperature above 70)°C, don't use it until you're repaired! Prolonged work in this mode can cause the processor to detach from the board.
8.Alternative solutions: custom firmware and battery replacement
If standard methods don’t help, consider:
- 📱 Install custom firmware (like LineageOS or Pixel Experience) that will remove MIUI And it can eliminate software lags.
- 🔋 Battery replacement – if the phone turns off at 20–30% charge, the battery is worn out.
- 🛠️ Memory chip soldering – if the diagnosis showed read/write errors.
The advantages of custom firmware for Redmi 9:
- ⚡ Higher productivity (no unnecessary services) MIUI).
- 🆕 Regular security updates (as opposed to official firmware).
- 🎨 Ability to fine-tune the interface.
Risks of custom firmware:
- ❌ Loss of warranty (if it is still valid).
- ⚠️ Possible bugs (e.g., non-functioning) NFC camera).
- 🔓 The need to unlock the bootloader (the process takes 7-14 days).
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Custom firmware requires unlocking the bootloader through the official Xiaomi website. Without this, it is impossible to install alternative software.