Why Xiaomi Redmi Note 9 Pro spontaneously reboots: a full analysis of the causes and solutions

Xiaomi Redmi Note 9 Pro is one of the most popular smartphones in the budget segment, but even it is not immune to unpleasant surprises. One of the most annoying problems faced by owners of this model is spontaneous reboots. The phone can turn off and turn back on at the most inopportune moment: during a conversation, playing, shooting video or just in standby mode. What is the reason for this behavior and how to fix it?

The reasons for the Redmi Note 9 Pro’s constant reboots fall into two big groups: software (related to firmware, apps, or settings) and hardware (issues with hardware—battery, motherboard, contacts). In this article, we’ll break down both categories, offer step-by-step diagnostic instructions, and give recommendations on when to contact the service center and when to manage it yourself.

It's important to understand that if the reboot started after a fall, moisture or mechanical impact, it's likely a hardware problem. MIUI or installing a new application, it's the software's fault. Let's start with the simplest and most obvious reasons.

Failures in firmware operation MIUI

Operating system MIUI Xiaomi is known for its abundance of features, but sometimes these functions work incorrectly:

• 🔄 Unstable firmware version (especially after major updates).
• 🐞 A bug in the core of the system that causes a critical failure (kernel panic).
• 📱 Shell conflict MIUI (For example, after rooting or installing a custom theme).

The first thing to do is check the current version. MIUI. To do this, go to the Settings. → The phone. → Version. MIUI. If your version is older than 12.5 but hasn’t been updated in a long time, you should install the latest stable firmware:

1. Open Settings → Update the system.
2. Click on "Check Updates."
3. If a new version is available, download and install it (preferably via Wi-Fi).

If the update didn’t work or the phone is restarting during the update, try resetting to factory settings.Warning: this will delete all data from the device, so make a backup beforehand.

Save Contacts in Google Account|Copy photos and videos on PC/cloud|Record data from accounts (social networks, banks)|Make sure your phone is at least 50 times charged%-->

⚠️ Warning: If the phone still restarts after resetting, the problem may be in the damaged part of the system, in which case only a complete flashing through Fastboot or Mi Flash Tool will help.

2. Application conflict or viruses

Sometimes the cause of spontaneous reboots is the side of the application, especially if they:

• 🔓 Request the rights of the superuser (root).
• 🕵️ Work in the background with high priority (antiviruses, optimizers).
• 🎮 They use non-standard API (game cheats, modified APK).

To identify a problem application, follow the following steps:

1. Load your phone in Safe Mode (hold the power button) → long tap on "Switch off» → «Safe regime»).
2. Watch the device for 1-2 days, and if the reboot stops, one of the installed applications is to blame.
3. Remove suspicious programs, starting with the last ones installed.

Pay particular attention to:

• 🛡️ Antiviruses (e.g. Avast, 360 Security) often conflict with the security system. MIUI).
• 🎮 Game launchers (Game Turbo, Xiaomi Game Center).
• 🔄 Applications for automatic cache cleaning (Clean Master, CCleaner).

If you suspect a virus, scan your phone through Malwarebytes or Dr.Web Light. Some malware masquerades as system processes and causes reboots to hide its activity.

Social networks and messengers|Games (PUBG, Genshin Impact et al.)|Antiviruses and optimizers|Castom launchers/themes|None of the above.-->

3. Battery problems

The Redmi Note 9 Pro has a 5020 mAh battery, but it gets worse over time, and if the phone reboots at a low charge level (e.g., 15 to 30%) or shuts down even at 40 to 50 percent, it's the battery's fault.

• 🔋 The phone discharges quickly (less than 4-5 hours with moderate use).
• 🔌 Charging is jerking or interrupted.
• 🌡️ The body is warming up in the battery area.
• 🔄 Reboots occur when connecting / disabling charging.

Check the status of the battery through the hidden menu:

1. Enter the dialer code ##4636##.
2. Select "Battery Information".
3. If you look at Battery Health, if it's below 80 percent, you should change the battery.

It is also useful to check the voltage and charging current with the AccuBattery app (available on Google Play).Normal readings for the Redmi Note 9 Pro:

If the battery is worn out, it will cost 1500-2500 to replace it. ₽ (Don't buy cheap ones, they can swell or damage the motherboard.

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Before you change the battery, try calibrating it: completely discharge the phone before you turn it off, then charge it to 100% without interruption, sometimes helping to restore the correct readings of the controller.

4. Processor overheating

Redmi Note 9 Pro is built on Qualcomm Snapdragon processor 720G, If the phone reboots during games, shoot a video. 4K or with prolonged use of the navigator, the reason is thermal throttling (emergency shutdown due to overheating).

How to check the temperature:

1. Install the CPU Monitor or AIDA64 app.
2. Run the load (for example, Genshin Impact on maximum settings).
3. Watch the core temperature of the CPU.Critical threshold for Snapdragon 720G — 90–95°C.

Causes of overheating:

• 🔥 Clogged radiator or thermal paste (dust, dirt inside the enclosure).
• 🎮 High-demand games (e.g. Call of Duty Mobile on ultra-graphics).
• ☀️ Use in the sun or in a hot room.
• 🔌 Fast charging (especially if you use a non-original power supply unit).

Decisions:

• 🧹 Clean the charging connector and vents (if any) from dust.
• 🎚️ Limit performance in settings: Settings → Battery → Performance mode → Balanced.
• 🛠️ If the phone is warming even in a simple, it may be necessary to replace the thermal paste (this is done in the service center).

5. Failures of the motherboard or contacts

If all software methods are tried and the phone is still restarted, the problem may lie in the hardware.

• 🔌 Battery contacts (oxidation, pollution).
• 📱 Memory. eMMC/UFS (wear after prolonged use).
• 🔧 Power supply chips (burnout due to voltage surges).
• 📡 Antenna module (if reboots occur when calls are made).

Diagnosing hardware problems on your own is difficult, but there are several signs:

• 🔄 The phone is rebooted at any physical impact (shaking, pressing the body).
• 🔋 Artifacts (strips, flickering) appear on the screen before the reboot.
• 📵 Reboots are accompanied by clicks or cracks from the speaker.
• 🔌 The phone does not turn on without a connected charger.

If you see any of these symptoms, it is not recommended to try to fix the phone yourself. ₽, repair of the fee can cost 3000-8000 ₽ depending on the breakdown.

⚠️ Note: If the phone reboots when connected to charging and sparks the connector USB-C, Stop using immediately! This is a sign of a short circuit that could cause a fire.

6.Problems with SIM-map

Rarely, but it happens that the Redmi Note 9 Pro restarts due to modem malfunctions or conflicts with the system. SIM-It's like this:

• 📶 The phone is turned off when you call or SMS.
• 🔄 Reboots occur when you change the network (for example, when switching from the network to the network). 4G on 3G).
• 📱 A notification appears on the screen «SIM-The map is removed, although it is in place.

How to check:

1. Extract. SIM-map and inspect it for damage or oxidation of contacts.
2. Try inserting another one. SIM-Card (preferably from another operator).
3. Switch to network settings on Only 3G (Settings → SIM-maps and mobile networks → Preferred type of network).

If the problem has disappeared, the reason is:

• 📱 Faulty. SIM-card (replace it in the operator’s cabin).
• 📡 Poor coverage 4G/5G (The phone is trying to reconnect and crashes).
• 🔧 Modem malfunction (reflashing or repair required).

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If the phone is rebooted only when calling, but with a different SIM-The card is working normally - the problem is in the operator's profile. SIM.

7. Mechanical damage after falling or moisture

Redmi Note 9 Pro has no official water protection (IP-certification), so even a small ingress of moisture can cause corrosion of contacts. If the phone fell, got wet or was in high humidity, check:

• 💧 Moisture indicator (white circle under the tray) SIM-If it is red, there was water).
• 🔌 Charging connector for the presence of oxidation.
• 📱 Screen – if under the glass you can see the stains, moisture got inside.

What to do:

1. If the ingress was recent (less than 24 hours ago), do not turn the phone on. Put it in a bag of silica gel (or rice) for 48 hours.
2. If the phone is already turned on, but it is unstable, contact the service for cleaning the board with ultrasound.
3. If there are cracks on the screen or dents on the body after the fall, check the integrity of the plumes and contacts.

The cost of repair after getting moisture:

If the phone reboots only when you press a certain part of the case, it's a sign of a break in the contacts inside, for example, pressing the lower left corner can cause the power button to close.

What do you do if nothing helps?

If you’ve tried all the ways, but the Redmi Note 9 Pro keeps rebooting, there are two options left:

1. Reflash the phone manually via Fastboot (instructions are on the forum) 4PDA).
2. Contact the service center for deep diagnosis.

Before the service visit:

• 📋 Write down all symptoms (when and how reboots occur).
• 🔋 Make sure the problem is not with the charger or cable.
• 📱 Backup your data (if the phone is still on).

Average repair prices in official Xiaomi services (for 2026):

• 🔧 Diagnosis - 500–1000 ₽.
• 🔋 Battery replacement: 1800–2500 ₽.
• 📱 Maintenance of the motherboard – from 3000 ₽.
• 🔄 Flashing - 1000-1500 ₽.

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If the phone is warranty, don't try to repair it yourself! opening the case or flashing the warranty will void.

FAQ: Frequent questions about Redmi Note 9 Pro reboots