Why the screen does not light up on Xiaomi Redmi 9 when incoming call: 7 reasons and ways to solve

Are you missing important calls because Xiaomi Redmi 9 is not responding to incoming calls? The screen is black even though the phone rings or vibrates? This problem is common among many users of Xiaomi budget smartphones, and its causes can be due to both system settings and hardware malfunctions. Unlike flagship models, where such bugs are quickly fixed with updates, owners of Redmi 9 often have to deal with it themselves.

In this article, we will not just list the possible causes, but give step-by-step instructions tailored to the specifics of the Redmi 9 (model M2003J15SC/M2003J15SS), you will learn how to check the proximity sensor, reset the settings without losing data, and when exactly it is time to carry the phone to the service, and also reveal a little-known power saving bug in MIUI 12.5, which provokes a black screen when calling.

1.Approximation sensor check is the first reason for the black screen

On Xiaomi Redmi 9, the infrared proximity sensor located next to the front camera responds to turn off the screen while you're calling, and if it's contaminated or defective, the phone thinks you've already brought the device to your ear, and it doesn't turn on the display. How do you check that?

Method 1: Call your phone and swipe your finger at the sensor area (top of the screen, left of the camera). If the screen lights up, the sensor is working, but it may be contaminated. Method 2: Use the test code to diagnose:

##6484##

Once you enter, you will open the Manual Test → Proximity Sensor menu. Close the sensor with your hand, the value should change from 5 to 0. If there is no reaction, the sensor is defective.

• 🔍 Sensor contamination: Wipe the area around the camera with an alcohol wipe (without pressing!).
• 🛠️ Train damage: If the sensor does not respond in the test, contact breaks are possible (disassembly is required).
• 📱 Software glitch: Sometimes rebooting or resetting sensor settings helps (more on this below).

⚠️ Warning: Do not use abrasive materials or acetone-based liquids to clean the sensor – this can damage the infrared sensor.

2. MIUI settings that lock the screen when you call

Xiaomi Redmi 9 runs on MIUI, a proprietary shell where some energy saving features can conflict with call processing.

1. Battery Mode: Go to Settings → Battery → Battery Mode and select Balanced. In Energy Saving Mode, the system can lock the screen to save charge.
2. Automatic Screen Shutdown: In Settings → Screen → Sleep mode set a value of at least 30 seconds. Too short a timeout sometimes works during a call.
3. Raise to wake up: Turn it off in Settings → Screen → Raise to wake up if it is active – it may conflict with the proximity sensor.

Pay special attention to the permissions for the application “Phone”:

• 📞 Open the Settings. → Annexes → Application management → Phone.
• 🔧 Check that the app has rights to display over other windows and Auto Run.
• 🔄 If the rights are disabled, turn them on and restart the phone.

3. Software glitches: cache, updates and "hard" reset

If the problem occurs after updating MIUI or installing new applications, it may be the fault of the damaged cache system or software conflict.

Step 1: Go to Settings → Applications → Application Management.

Step 2: Find the Phone app, open its settings and click Clear Cache.

Step 3: Repeat the same for the Contacts app.

If that doesn’t help, try resetting your network settings (does not delete data, but resets connections):

→ SIM-maps and mobile networks → Network reset

The last measure is a factory reset. Before you do that, back up your data through Settings → About Phone → Backup. To reset:

Settings → About the phone → Reset settings → Erase all data

⚠️ Warning: After resetting to Redmi 9, you may need to re-activate your Mi Account!

Hardware malfunctions: from plume to battery

If software methods don't work, the problem may be physical damage, and here are the most common "iron" reasons for the Redmi 9:

• 🔌 Display plume: When you fall or vibrate, the contacts of the plume connecting the screen to the motherboard may move away.Symptom - the screen does not respond to touch or does not turn on when you call, but the phone rings.
• 🔋 Bloated battery: On the Redmi 9 (especially after 1.5-2 years of use), the battery can swell and press on the plumes or screen.
• 📱 Damage to flexible proximity sensor cable: A common problem after replacing the screen in an “artisanal” way – masters forget to connect or damage the sensor plume.
• 🔧 Motherboard malfunction: Less common, but it happens that the screen power controller fails, in which case the screen may not turn on in other situations (for example, when charging).

How to check hardware problems without disassembly?

1. Connect your phone to charge, and if the screen doesn't respond to charging, it's more like a plume or a board.
2. Try a hard reboot: press Power + Volume up for 10-15 seconds. If the screen is running after that, it's the software.
3. Light a flashlight on the screen during the call. If you see a dim image in the dark, the problem is in the backlight (train or inverter).

5. Conflicts with shells and third-party applications

Many Redmi 9 users install third-party launchers (Nova, Apex) or screen locking apps (such as Smart Lock) that can intercept screen control and conflict with system calls. How do you fix that?

Step 1: Return the standard launcher:

1. Go to Settings → Applications → By default.
2. Select Launcher and install MIUI Launcher.
3. Reboot the phone.

Step 2: Check the applications with administrator rights:

• 🔒 Open the Settings. → Passwords and security → Privileges of the device administrator.
• 🚫 Disable rights for all third-party applications (except system applications).
• 🔄 Restart your phone and check the calls.

Step 3: Remove conflicting programs:

The most problematic applications for Redmi 9:

• 📵 Truecaller (can block the system interface of calls).
• 🔒 AppLock or Smart AppLock (sometimes locking the screen while calling).
• 🌙 Twilight or Night Shift (change screen brightness and may conflict with proximity sensor).

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If you don’t want to delete the app but suspect it of conflict, add it to Battery Exclusions (Settings → Battery → Battery → All Apps) and select No Limits.

6. Update firmware and rollback to stable version of MIUI

Some versions of MIUI 12.5 and MIUI 13 for Redmi 9 had a bug that prevented the screen from turning on when the phone was incoming if the phone was down.This issue was officially confirmed by Xiaomi in V12.5.1.0.RJCMIXM and V12.5.2.0.RJCMIXM firmware versions.

How to update firmware:

1. Go to Settings → About the phone → System update.
2. Click Check Updates and install the latest version.
3. If you don’t have an update, download it manually from MIUI Downloads (select Redmi 9 or M2003J15SC).

How to Reverse to the Previous Version:

This will require an unlocked bootloader and the Mi Flash Tool.

1. Download the desired firmware version (e.g. V12.0.10.0.QJCMIXM) from the Xiaomi website.
2. Unclose the file and place the folder in the root of the C:\ disk.
3. Download the phone to Fastboot mode (clip Power + Volume down).
4. Connect to your PC, open the Mi Flash Tool, select the firmware folder and press Flash.

⚠️ Attention: Firmware rollback erases all data! Also, after this procedure, you may need to re-assign your Mi Account account.

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If the problem occurred after the MIUI update, try resetting the settings first through Settings → About Phone → Resetting. 60% of the time, this helps without rolling back the firmware.

7.When to contact the service: signs of serious breakdowns

If you’ve tried all the methods, but the screen on Redmi 9 still doesn’t turn on when calling, it’s time to contact the specialists.

• 🔧 The screen does not respond at all (even when charging or switching on).
• 📱 Vertical stripes or artifacts appeared on the screen.
• 🔋 The phone turns off at a charge level above 20%.
• 🔊 The sound during the call is distorted or lost.
• 🌡️ The phone is overheating even without loading.

The cost of repairing Redmi 9 in service centers (in Russia, 2026):

Where to repair it:

• 🏢 Xiaomi service centers: 6-12 months warranty, but more expensive by 20-30%.
• 🔧 Local workshops: Cheaper, but check reviews and ask for a guarantee.
• 📦 Self-replacement: Only if you have experience (details for Redmi 9 start at 300) ₽ AliExpress).

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Before visiting the service, back up your data via Settings → About Phone → Backup or using the Mi PC Suite program on your computer.

FAQ: Frequent questions about the black screen on Redmi 9