Xiaomi Redmi Note 9 is still one of the most popular budget smartphones, but many users face its sudden freezes. The smartphone can “slow down” in games, do not respond to touch, hang on the logo when you turn on or completely reboot for no reason. In 90% of cases, the problem can be solved by yourself without contacting the service center.
In this article, we will look at all possible causes of freezes, from overloaded memory to hardware malfunctions, as well as give step-by-step instructions for diagnosis and elimination. Particular attention will be paid to typical user errors that make the situation worse (for example, installing “cleaners” or unofficial firmware). If your Redmi Note 9 started to glitches after a MIUI update or a fall, here you will find a solution.
For convenience, we have divided the materials into blocks: first, software reasons (can be fixed at home), then hardware (repair required), at the end of the article - FAQ with answers to frequent questions and a survey for owners of the Redmi Note 9.
1.Overloaded memory: the main culprit of lags
The most common cause of freezes is a lack of RAM or internal memory. The Redmi Note 9 as standard has only 3GB of RAM and 64GB of ROM, which quickly becomes a bottleneck when used actively. If less than 10% of memory is free, the system begins to “brake” due to the constant reboot of applications.
How to check:
- 📱 Open the Settings. → The phone. → Memory and see the usage schedule.
- 🔍 Go to Settings. → Annexes → Application management and sort by size.
- ⚡ Use third-party utilities like Files by Google or SD Maid for garbage analysis.
What to do:
- Remove the app cache through Settings → Memory → Cleanup (not to be confused with a full reset!).
- Transfer photos and videos to a memory card or cloud (Google Photos, MI Cloud).
- Turn off the autoload of unnecessary applications in Settings → Battery → Autostart.
- If you have less than 5GB of freeware, remove unused programs or games.
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Don't install the Play Market memory cleaners, they only make the lags worse by constantly working in the background. MIUI already has all the necessary optimization tools built in.
2. Failures after the MIUI update: how to roll back or fix
Many freezes start after the MIUI is automatically updated to 12.5+ or 13, and the problem is with unoptimized code for low-end processors (Redmi Note 9 has MediaTek Helio G85), as well as bugs in the Android kernel.
- 🔄 Endless reboot on the Redmi logo.
- 🐢 Strong lags when scrolling through menus or opening apps.
- 📵 No network after update (modem is not initialized).
Decisions:
- Recovery rollback: Turn off your phone, press Power + Volume up to log in to Recovery. Select Wipe Data → Wipe All Data (full reset!). Go to Reboot → System.
- Handheld firmware via Fastboot: Download the official firmware for your model from Xiaomi's website. Unpack the archive and launch flash_all.bat PC with Mi Flash Tool drivers installed.
What if the smartphone does not turn on after the update?
⚠️ Note: Do not install custom firmware (such as LineageOS) without unlocking the bootloader - this will lead to a "brick" (complete inoperability) of the device. Redmi Note 9 has Anti-Rollback protection, which blocks rollback on older versions. MIUI.
3.Overheating: When a smartphone 'strangles' itself
The MediaTek Helio G85 in the Redmi Note 9 is prone to overheating due to poor thermal paste and compact body. At temperatures above 60°C, the processor begins trottling (forced frequency reduction), which causes freezes.
- 🎮 During games (PUBG Mobile, Genshin Impact).
- 📹 With long-term video shooting in 4K.
- ☀️ In hot weather or when charging "fast" charging.
How to diagnose:
- Install the AIDA64 app and check the temperature in the Sensors section.
- If the CPU temperature exceeds 70°C, it is critical overheating.
Decisions:
- 🛠️ Replacement of thermopaste: In the service center (cost) ~1500 rubles.. It is not recommended to do it yourself - there is a high risk of damaging the plumes.
- 🔋 Turning off fast charging: Go to Settings → Battery → Charging settings and select Standard Charging mode.
- 🎮 Limitation FPS In the game graphics settings set a limit of 30-40 FPS.
| CPU temperature | Status. | Recommendations |
|---|---|---|
| To 45°C. | Norma. | No action is required. |
| 45–60°C | Increased load | Close the background applications, reduce the brightness of the screen. |
| 60–70°C | Overheating | Stop playing and let the smartphone cool down. |
| Over 70°C | Critical overheating | Replacement of thermopastes or diagnostics in the service is necessary. |
4.Battery problems: bloating and wear
The battery in the Redmi Note 9 (5,020 mAh) is designed for ~500 charge cycles, and after 2-3 years of use, its capacity drops by 30-40%, resulting in:
- ⚡ Sudden shutdowns at 20-30% charge.
- 🔄 Freeze when connecting charging (the battery controller fails).
- 📉 Quick discharge on standby.
How to check the wear:
- Enter the dialer code ##4636##.
- Go to Battery Information and see the Health Level parameter.
- If the value is below 70%, it is time to change the battery.
⚠️ Warning: If the smartphone body is swelling and the screen is starting to move away from the frame, turn off the device immediately! The bloated battery may ignite:
- Don't try to charge the phone.
- Don't puncture the battery.
- Contact the service for replacement (cost ~ 2000-2500 rubles).
The smartphone turns off at 20-30% charge|The body swelled or deformed.|The phone is warming up even without loading.|The swelling is going to stop (it will stop)|Working hours have been cut in half-->
5. Application conflicts: who is "slowing down" the system?
Some programs conflict with MIUI, causing the freezes, most often the culprits:
- 🛡️ Antiviruses (Avast, Dr.Web) – block system processes.
- 🔄 Launchers (Nova Launcher, Microsoft Launcher) – can conflict with the shell MIUI.
- 🎮 Game cheats (GameGuardian, Lucky Patcher) – disrupt the Android kernel.
- 📱 Acceleration applications (Clean Master, DU Speed Booster – You are using your own resources.
How to find a problem application:
- Go to Settings → Applications → Application Management.
- Sort by work time in the background.
- Remove or disable suspicious programs.
If the smartphone freezes after installing a specific application:
- Load to Safe Mode (hold the off button → long tap on “Stop” → “Safe Mode”).
- Remove the problem software.
- Reboot normally.
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The most reliable way to detect a conflicting application is to reset to factory settings and then install the programs one by one, and if the lags come back after installing the specific software, the culprit is found.
6. Hardware malfunctions: when without repairs can not do
If none of the software methods worked, the problem lies in the hardware.Typical hardware faults of the Redmi Note 9:
| Symptoms. | Probable cause | Decision |
|---|---|---|
| Freezes when connecting to Wi-Fi/4G | Communications module failure (Qualcomm WCN3990) | Replacement of the module (~3000 RUB) |
| Accidental reboots when pressing the body | Power button plume damaged | Replacement of the plume (~1500 rubles) |
| Artifacts on the screen + hangs | Detachment of the graphics chip (Mali-G52 MC2) | Solding chip (~5000 rubles) |
| Not turned on after falling | Damage to the motherboard | Diagnostics in the service |
⚠️ Warning: If your smartphone falls or gets wet, don't try to disassemble it yourself! Redmi Note 9 has fragile plumes, and getting moisture can cause contacts to corrosion:
- Turn off the device immediately.
- Don't plug the charger.
- Contact the service within 24 hours – the faster, the better the chances of saving the phone.
How to choose a service center:
- 🔧 Official Xiaomi Partners (list on site).
- 💰 Compare prices: replacement of the screen costs 4000-6000 rubles, battery - 2000-2500 rubles.
- ⏱️ Repair time: simple work (battery replacement) takes 1-2 hours, complex (soldier chips) - up to 3 days.
7. MIUI Optimization: Hidden Settings for Acceleration
MIUI has hidden features that help reduce lags. Here's what you can do:
Disable animation: Settings → Special. features → Remove animation | Activate performance mode: Settings → Battery → Performance mode | Disable MIUI Optimization: Settings → Additional → Regional settings → Select India region (reduces background processes) |Limit background activity: Settings → Battery → Autostart-->
Additional tweaks (require root):
- 🔧 Install the Perseus Kernel for better processor management.
- 📉 Disable miui.analytics and msa (Xiaomi data collection services).
- 🚀 Using Greenify to “freeze” background apps.
⚠️ Note: Getting root rights voids warranty and may cause Google Pay, Netflix and banking apps to fail due to SafetyNet.