Modern OLED and AMOLED arrays, which are installed in smartphones Xiaomi, Redmi and Poco, are characterized by high pixel density and color saturation. However, even premium panels can have a production defect or damage during operation. If you notice on the display strange dots that do not change color or glow differently than the surrounding area, most likely you have encountered a matrix defect.
It's important to understand the difference between software failure and physical failure. Sometimes broken pixels are confused with image freezes or GPU artifacts. Proper diagnosis allows you to determine whether the screen is software-recoverable or if you need to replace the module in the service center.
In this article, we will look at all the available ways to check the display, from built-in engineering tests to specialized applications, learn how to distinguish “burning” subpixels from completely dead zones and learn whether you can save the situation without visiting the master.
Types of Matrix Defects and Their Differences
Before you run tests, you need to understand the terminology, because the type of defect depends on how you fix it. Not all points on the screen are fatal breakages. There are three main types of anomalies that a user can detect when you look closely at the display of your gadget.
The first type is stuck pixels, which are constantly lit in the same color (red, green or blue) regardless of what is displayed on the screen, and these defects are often programmatically treatable, since the crystal is physically intact, but stuck in one position.
The second type is dead pixels, black dots that don't glow at all, in which case the transistor that controls the glow is out of order, it's almost impossible to recover a completely dead pixel because the electrical circuit is broken, and the third type is bright white dots, often a sign of dust falling under the matrix or serious damage to the backlight layer.
- 🔴 Stuck pixel – burns in one color, potentially repairable.
- ⚫ Dead pixel – black dot, requires a screen replacement.
- ⚪ Bright spot – often the result of a physical impact or dust.
⚠️ Note: If you find one or two black dots in the corner of the screen, this may be a standard manufacturing tolerance. ISO. The guarantee case usually occurs only in the presence of clusters (groups) of defective zones.
Use of the built-in CIT engineering menu
The most reliable and quickest way to check the screen on Xiaomi is to use the built-in CIT (Cellular Identity Tool) engineering menu, which is created by developers for initial diagnostics of the device and does not require the installation of third-party software.
To start the test, you need to open the standard application "Phone" and enter a special USSD-On most Xiaomi and Redmi devices, it's code ##6484##. If the combination doesn’t work, try it ##4636## Or go through the settings: Settings → The phone. → Version. MIUI (press 5-7 once).
Once you log in, select Screen or Display, and the system will suggest you to avoid cyclical color changes: red, green, blue, white and black, carefully examine the screen at each color, and you can see the burning points on the black background, and black dips on the white background.
☑️ Diagnosis through CIT menu
At the end of the test, the system will ask if the screen has passed the check. If you see defects, press Fail. This will not fix the screen, but will record an error log that can be useful when contacting the service center under warranty.
Online services and specialized applications
If the engineering menu is not available for some reason or you want to conduct a deeper diagnosis using video content, you should turn to third-party solutions. Online tests are convenient because they do not require the installation of unnecessary programs, which saves memory of the device.
One of the most popular sites is the Dead Pixel Buddy site, or similar services, which are simple: they deploy high-resolution color images to the full screen, and you can switch between modes to detect subpixel anomalies.
For Android, there are also powerful apps from Google Play, such as Test Your Screen or Dead Pixel Test, which allow you not only to change colors, but also to run complex patterns that help identify problems with the uniformity of the backlight or touchscreen.
- 📱 Dead Pixel Test is a classic application with a set of colors.
- 🌐 Online Screen Test – a web service for quick check without installation.
- 🎨 Display Tester – a professional tool with calibration.
Why can online tests be less accurate?
Testing with Video Content
Static images don't always reveal all the problems, and dynamic content like video can help you notice artifacts that only show up when frames change or a certain brightness, and it's particularly effective for finding problems with the matrix plume.
Upload a specially prepared color-shifting video to your phone, or search YouTube for "screen test video 4k." Play it to the highest quality and deploy it to the full screen. Pay attention to the boundaries of color transitions.
Often, broken points are not single points, but whole rows or columns that can flicker. The video test also helps to detect the "ghosting effect" when moving objects remain a color trail, indicating low response time of the matrix or wear.
It's recommended that you check at different brightnesses, minimize the brightness and unscrew it, and some defects only show up at low brightness levels when the control voltage on the crystals is minimal.
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Use a dark room to check. External light can shine on the screen and hide subtle defects, making the diagnosis ineffective.
Results analysis and defect table
After all the tests, you have to systematize the data. Not every point is a defect. Manufacturers use ISO standards that allow for a certain number of defective pixels depending on the class of the matrix.
Here is a table that will help you classify the anomalies you find and determine their criticality, and keep this information if you plan to argue with a vendor or service center.
| Type of defect | Appearance | Reason. | Decision |
|---|---|---|---|
| Dead Pixel | Black spot | Breaking the power chain | Screen replacement |
| Stuck Pixel | Colored dot (RGB) | Crystal sticking | Warming up/Massage |
| Hot Pixel | Bright white dot | dust or breakdown | Replacement of the module |
| Burn-in | Shadow from the interface | Organic burnout | No cure. |
Note the term Burn-in. On Xiaomi AMOLED screens, this is a common occurrence after long periods of use. Static interface elements (status strips, navigation buttons) leave a barely noticeable trace. These are not broken pixels, but uneven wear of the organic layer.
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The presence of 1-2 bit pixels in the center of the screen is often the basis for warranty replacement, while defects at the edges can be recognized as the norm.
Recovery and prevention methods
If the diagnostics show that there are stuck (color) pixels, you can try to restore their performance, the method is based on a rapid change of colors, which can "stir up" the jammed crystal, and there are special programs flashing.
One of the popular methods is to massage the screen neatly, turn off the phone, take the soft cloth and massage the area of the defect in a circular motion without much pressure. Then turn on the device, which is risky and can damage the touchscreen, so use it at your own risk.
To prevent burnout of AMOLED matrices on Xiaomi, it is recommended:
- 🌑 Use a dark interface theme.
- 🔄 Periodically change the wallpaper.
- 🔅 Do not keep the brightness 100% constantly.
⚠️ Warning: Software recovery only helps in case of stuck pixels. If the dot is black (dead), no applications and massages will bring it back to life - only replacing the display will help.
Warranty cases and return of the device
The issue of returning a phone with a defective screen is often a subject of controversy, and under consumer law, a significant defect is considered to be an ineradicable defect or defect that has manifested itself repeatedly, but the number of broken pixels is regulated by GOST.
Usually, a warranty case is considered to be the presence of more than 3-5 dead pixels in the work area or a cluster of several points in the center of the screen. If the defect is one and is located at the edge, the seller can refuse to replace, citing acceptable norms.
When contacting the service center, be sure to show the test results CIT. If the phone is new, it is best to make a return within 14 days, not arguing it with broken pixels (as it is a technically complex device), but referring to a general quality mismatch.