Xiaomi smartphone started to brake, quickly discharge or behave strangely after a fall? 70% Failures can be identified at home for 10-15 minutes with standard tools and hidden functions MIUI. This article will help to check all the key nodes of the device: from the display and battery to communication modules and iron, without disassembling the case.
We have collected the latest diagnostic methods for 2018-2026 models (including Redmi Note 12, POCO X5, Xiaomi 13T And so on, that work even without root rights, and you don't need any special software -- just your hands, your charger, and a couple of free Google Play utilities -- and if you find a problem, you'll know if you should fix your phone or if it's easier to buy a new one.
1. Quick check of external damage: what to look for before turning on the phone
Before testing the internal components, inspect the body for physical defects that can affect the operation of the device. Even a small crack in the back sometimes leads to detachment of antenna contacts or moisture.
Take a flashlight and check carefully:
- 🔍 Screen: microcracks (even without chips), "spiders" at the corners, stratification of oleophobic coating (checked by holding a finger - if there are greasy traces, the coating is erased).
- 📱 Body: dents on the aluminum frame (especially at connectors), detachment of plastic inserts (relevant to Redmi) 9/10).
- 🔌 Connectors: Contorted contacts in USB-C 3.5 mm (check for light - should shine, without oxidation).
- 💧 Moisture indicators: white or red dots inside the holes for SIM-stains and stains (if they were red, they were stained).
Critical finding: if the moisture indicator under the battery (as seen when removing the back cover) is red, even after a complete drying, problems with the motherboard may occur after 3-6 months, in which case it is better to stop the diagnosis and take the phone to the service.
⚠️ Warning: Do not confuse scratches on the screen with internal cracks in the matrix, the latter are visible only when the display is turned on (colored stripes or "stars" appear when pressed).
2.Display Testing: How to Identify Broken Pixels and Sensor Problems
The screen is the most vulnerable element in a smartphone, and even after a minor impact, you can get dead pixels, color reproduction or calibrate your sensor, and use the built-in diagnostic menu or third-party apps to check.
Method 1: Hidden screen test (works on all Xiaomi devices) MIUI 10+):
- Open the Phone app.
- Enter the combination: ##6484### (or #223### for new models).
- Select Display Test and consistently check all colors (red, green, blue, black, white).
Method 2: Check the sensor through the Touch Screen Test (download from Google Play).
- 🎨 Multitouch: how many fingers the screen recognizes at the same time (the norm is 10 points for flagships, 5-7 for state employees).
- ⚡ Response delay: If lines are drawn more than 50ms late, the sensor needs to be replaced.
- 🔄 "Ghost" presses: if the screen appears dots without your touch - a problem with the plume.
| Symptoms. | Possible cause | Decision |
|---|---|---|
| Colored stripes around the edges of the screen | Separation of matrix plume | Replacement of the plume 2,000–4,000 ₽) |
| The screen flashes at brightness >70% | Failure of the lighting or driver | Diagnostics in the service (display module replacement is possible) |
| "Ghost" presses in one corner | Damage to the sensory layer | Replacement of touchscreen (from 3,500) ₽) |
| Yellow on a white background | Matrix burnout (OLED) or (LCD) | For OLED — screen replacement, for LCD — calibration |
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If the Xiaomi screen started to “ribble” when scrolling, try turning on Settings in the settings → Display. → Frequency of update → 60 If the ripples disappear - a problem in the driver of high frequency (relevant to the POCO F4/F5).
Diagnostics of the battery: how to find out the real wear without disassembly
The battery is the second most popular source of problems after the screen, and even if the phone is holding the charge "normally", the latent wear can reach 40-50%, which leads to sudden shutdowns at 20-30% charge.
Method 1: Engineering menu code
Enter the phone combination in the app: ##4636## → Select Battery Information. Pay attention to the:
- 🔋 Charge level: if it shows 100% and the phone is off by 80%, the calibration is down.
- 🌡️ Temperature: above 40°C when charging - a sign of degradation.
- ⚡ Voltage: Normal for Li-Pol - 3.7–4.2V. If below 3.5V — battery critically worn.
Method 2: AccuBattery Appendix (most accurate)
Install the utility and charge the phone from 0% to 100% without interruptions. After 3-5 charging cycles, the app will show:
- 📊 Real capacity (compare with passport: for example, for Redmi Note 11 norm – 4900-5000 mAh).
⚠️ Note: If the AccuBattery has a capacity of less than 70% of the passport, and the phone turns off at 15-20% charge, the battery must be replaced urgently.
Make a backup copy of the data|Check the originality of the battery (code on the sticker must match the phone model)|Use the mediator to carefully disconnect the plume|Avoid contact of the new battery with metal objects|Glue a new battery with a heat paste (for better heat sink)-->
4. Checking of speakers, microphones and audio track
Sound problems on Xiaomi are often disguised as software failures, although the cause is physical damage, such as a speaker's contact breaking off or a microphone clogged with dust after a fall.
Dynamics test:
- Turn on the bass track (such as this test) and check:
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Speaker Test
Microphone test:
Use the Microphone Test app (or standard voice recorder):
- 🎤 Main microphone (bottom): Record the sound from a distance of 30 cm – the voice should be clear.
- 📱 Noise-canceling microphone (top): check in a noisy room - if background sounds are not suppressed, the microphone is faulty.
- 🔇 Call microphone: Call another phone and make sure the person is clearly listening.
Frequent problems and solutions:
| Symptoms. | Reason. | Decision |
|---|---|---|
| Wheezing in dynamics at maximum volume | Dust or membrane damage | Blow compressed air or replace the speaker (from 800) ₽) |
| The interviewer can’t hear you during the call. | Oxidation of microphone contacts | Cleaning with alcohol or replacing a microphone module (1,200–1,500) ₽) |
| The sound disappears when the phone is tilted. | Bad contact plume speaker | Interpling of the plume or replacing the audio module |
How to clean the speaker without disassembly?
5. Camera testing: from focus to infrared sensor
Xiaomi’s camera modules often fail after falls or moisture.Even if the main camera is working, there may be problems with autofocus, stabilization, or additional sensors (wide-angle, macro, ToF).
Basic test:
- Open the standard Camera app and check:
- Check the additional cameras:
Advanced diagnostics:
Install the Camera. MX Manual Camera and Manually Check It Out:
- 📏 Exposure: if in exposure >2 seconds photo is blurred - defective gyroscope (needed for stabilization).
- 🎛️ White balance: if the colors are heavily distorted in manual mode - a problem with the light sensor.
- 🔄 Switching cameras: if the change of modules screen "hangs" - a failure in the firmware or damaged plume.
⚠️ Warning: If the camera fails to connect to the camera after a fall, do not try to reboot the phone repeatedly. This may be a short circuit in the module, which, if you try to turn on again, will damage the motherboard.
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If the main camera is working and the secondary camera (wide-angle/macro) is not, 90% of the time the laminated plume is to blame, and it costs 1,500 to 2,500 to replace it. ₽, The new camera module costs 5,000 to 10,000 ₽.
6. Verification of communication modules: Wi-Fi, Bluetooth, GPS mobile
Communication problems on Xiaomi are divided into two types: software (solved by resetting settings) and hardware (required repairs).
Wi-Fi and Bluetooth:
- 📶 Wi-Fi speed: connect to a 5GHz network and check the speed on Speedtest. If below 50% of the tariff, there is an antenna problem.
- 🔄 Stability: If Wi-Fi is turned off when loaded (for example, when downloading a file), the communication module or firmware is to blame.
- 🎧 Bluetooth: plug your headphones and step back 10 meters. If the connection breaks, a weak signal (possibly antenna oxidation).
Mobile network and GPS:
- 📡 Signal strength: enter ##4636## → Phone information. If dBm is lower -100 — weak signal (problem with antenna or SIM-card).
- 📍 GPS: Turn on Google Maps and check the accuracy of the location. >50m - faulty GPS-module.
- 🔄 Network switching: if the phone does not catch 4G/5G In the coverage area, check the settings APN Or reset them through Settings. → SIM-maps and mobile networks → Access points (APN) → Reset.
Frequent hardware problems:
| Symptoms. | Reason. | Decision |
|---|---|---|
| Wi-Fi only works next to the router | Wi-Fi antenna damage (often after falling) | Replacement of the antenna module (1500–2500) ₽) |
| Bluetooth does not find devices | Failure in the Bluetooth module or firmware | Flashing or replacement of a chip (from 3 000) ₽) |
| GPS Identifies the location with error >100 m m m | Malfunction GPS-antennae | Diagnostics in the service (maternity board replacement is possible) |
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If the mobile network disappears when the phone is tilted, the problem is contacts. SIM-Try putting thin paper under the tray for better pressing or replace the tray (worth it). ~300 ₽).
7. Diagnostics of iron: processor, memory and sensors
If the phone starts to brake, overheat or spontaneously reboot, the problem may lie in the processor, RAM or sensors.
Processor and memory test:
- Install. CPU Throttling Test and run the test. If the processor frequency drops below 50% of the maximum (for example, the Snapdragon 8 Gen 2 must hold 3.2 GHz) - there is a trottling (limit due to overheating).
- Check the RAM through AIDA64 (section Memory. If used RAM constantly >80% - possible memory leakage (software fault or chip damaged).
Sensor check:
Enter the code ##6484## → Sensor Test. The test should show:
- 🧭 Gyroscope/accelerometer: when rotating the phone, the values should change smoothly (trucks are a sign of malfunction).
- 🧲 Magnetic sensor: bring a magnet - values should change dramatically.
- 💡 Light sensor: Close the top of the phone with your hand – the brightness of the screen should decrease.
- 👆 Approximation sensor: during the call, the screen should go out when lifted to the ear.
Frequent problems with iron:
| Symptoms. | Reason. | Decision |
|---|---|---|
| The phone turns off when loaded (games, video shooting) | Overheating of the processor due to dried thermal paste | Replacement of thermopaste (1500–2500) ₽) heat-stamp |
| Apps are crashed with the error "Insufficient memory" | Damage to the RAM chip | Replacement of motherboard (from 8000) ₽) |
| The screen does not rotate when you turn the phone. | Failure of the gyroscope or accelerometer | Sensor replacement 2,000–3,500 ₽) slush |
8. Final check: hidden tests and when to contact the service
If after all the tests you did not find obvious malfunctions, but the phone still works unstable, run a full diagnosis through a hidden menu:
- Enter the code ##2834## (for new models) or ##6484## (for older models).
- Select the Manual Test and check all the items consistently.
- Pay attention to the points marked FAIL — They indicate faulty components.
When exactly need help from the service:
- 🔧 The phone is not powered on or loaded only in Fastboot.
- 🔥 Overheating without load (more than 50)°C on standby).
- 💾 is not defined by internal memory or SIM-map.
- 📵 The network disappears after the firmware update.
- 🔋 The battery swelled (sees from the rear panel raised).
What you can fix yourself:
- 🔄 Reset settings through Settings → The phone. → Resetting (helps in 30% of software failures).
- 📥 Flash your phone via Mi Flash Tool (instructions at xiaomiflash.com).
- 🔌 Replace the battery or screen (there are video instructions for most models).
⚠️ Warning: If the phone turns on after falling but does not see SIM-If you're not charging, don't try to disassemble it yourself, and 60 percent of the time, it causes plumes to be damaged and repairs to cost more.
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Most Xiaomi malfunctions (except for physical damage to the board) are cheaper to repair than buying a new phone. For example, replacing the screen on the Redmi Note 11 costs 4,000-6,000 dollars. ₽, The new phone is from 15,000. ₽.