Xiaomi, Redmi and POCO smartphone owners often face the need to quickly diagnose the display immediately after purchasing a device or when the first signs of malfunction appear. Screen check is critical, as it is the matrix that bears the brunt of transportation and daily operation. Fortunately, the MIUI and HyperOS shells have powerful tools for self-analyzing the state of the matrix without going to the service center.
There are several ways to detect defects, from using an embedded engineering menu to running specialized test applications.Display diagnostics can detect broken pixels, color problems, broken touchscreen zones and image artifacts. The fastest and deepest method is to enter a special USSD-commands that open access to the hidden menu CIT (Customer Integration Test: This approach does not require third-party software installation and provides the most accurate results.
In this article, we will take a look at all the available verification methods, including engineering login codes and visual tests, how to distinguish software failure from physical damage, and what steps to take if tests reveal anomalies, and proper calibration and verification will help maintain warranty or reasonably require replacement of the device.
CIT Engineering Menu: Entry through Code Combinations
The main tool for deep diagnostics of the hardware of the smartphone is the engineering menu. To get into it, the user needs to enter the sequence of characters in the Phone application. For Xiaomi devices, the command ##6484## is the most relevant. In some cases, especially on older versions of firmware or regional assemblies, the code ##4636## can work, although it is more often responsible for network and battery information.
Once you enter the last digit or menu symbol, the CIT should open automatically. If this does not happen, it is possible that your version of the MIUI shell has limitations for your region, or the code was entered with an error. In this case, you can try an alternative way through the settings: go to Settings → About Phone → All settings and quickly click 5-7 times in a row on the "Kerole Version".
⚠️ Warning: Be very careful when you're on the engineering menu. Don't change settings that you don't know the value of, especially those related to the radio module or sensor calibration, if you're not sure what you're doing.
The menu interface is a list of tests, each signed or icon-readable. We're interested in the section that's responsible for the display. Depending on the firmware version, it can be called Display, Screen or Touchpanel. This is where the basic defect tests are conducted.
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The ##6484## code works on 95% of Xiaomi devices without having to get root permissions or connect to a computer.
Diagnostics of the matrix: search for broken pixels
One of the most common problems with modern OLEDs and IPS matrices is the appearance of broken pixels. These are microscopic dots that have stopped correctly displaying color or glowing. In the Xiaomi engineering menu, there is a special test that consistently paints the screen in different colors, which makes it easy to identify such defects.
To start the test, select Display or Screen. The screen will start to change colors: red, green, blue, white and black. Your task is to carefully examine the surface in good light. Broken pixels will look like black dots on a white background or, conversely, like bright glowing dots on a black background.
- 🔴 Red background: helps to identify problems with red subpixel or uneven backlighting.
- 🟢 Green background: most sensitive to the human eye, clearly visible defects in the structure of the matrix.
- 🔵 Blue background: often reveals "burnout" or degradation of organic elements in the AMOLED screen.
- ⚪ White background: ideal for finding black (dead) pixels and dust under glass.
- ⚫ Black background: required to detect lights and burning (stuck) pixels.
If you find multiple broken pixels, don't panic right away. Manufacturers allow a certain number of defective dots (usually 2 to 5 depending on the matrix class), which is not considered a warranty case. However, if the defects of one zone or their number is large, this is a reason to contact the service.
Can broken pixels be recovered?
Checking the performance of the touch screen
In addition to image quality, the responsiveness of the touchscreen layer is critical, and touchscreen problems can manifest as "dead zones" where the phone does not respond to touch, or "phantom taps" where the device performs actions on its own. CIT This is the Touchpanel test.
When you run the test, the screen becomes empty, and you're asked to swipe your finger across the entire display surface, and when you touch the lines, they should remain colored, cross-cross, diagonally, and carefully treat the edges of the screen, and if there's a line interrupted or not drawn at all, that's a sign of malfunction.
Multi-touch is also worth paying attention to. Modern Xiaomi smartphones support simultaneous recognition of 10 or more touches. In some versions of the test, you can press a special button to check the multi-touch and touch the screen with several fingers at the same time. All dots must be displayed correctly.
⚠️ Warning: Before checking the touchscreen, be sure to remove the protective glass or film if they are more than 0.3 mm thick or damaged.
Often, problems with the wheelbarrow arise after unqualified screen replacement or moisture. If the test shows non-functioning areas in the center of the screen, the device becomes impossible to use. In the case of edge defects, you can try calibration, but most often you need to replace the digitizer.
☑️ Signs of a faulty touchscreen
Color reproduction and gradient tests
Image quality is determined not only by the absence of broken pixels, but also by the uniformity of color reproduction. Cheap IPS matrixes or defective AMOLED panels can suffer from the effect of cloud spots or uneven glow at the edges. Gradient tests are used in the engineering menu to identify these problems.
In the Display section, select the gradient display mode. The screen will smoothly shimmer from one shade to another. Watch the transitions carefully: they should be smooth, without sharp jumps in brightness or banding.
You should also check the angles of view. Tilt the phone from different angles during the test. If the image fades, inverts or iridescents appear, this may indicate poor matrix quality or damage to the plume.
| Type of defect | It looks like | What a background you can see. | Criticism |
|---|---|---|---|
| A broken pixel | Point of black or bright color | Contrast (white/black) | Low (if few) |
| The Light (Clouding) | Bright spots, clouds | Dark background, black | Medium |
| Bandning (Streets) | Horizontal or vertical lines | Gradients, gray | Tall. |
| Yellow spots | Local yellow areas | White background | Medium/High |
Defects like uneven lighting are common in budget models and are not always a marriage, but if stains interfere with reading text or watching videos, this is a reason for returning the goods within 14 days.
Use of online services and applications
If you have no access to the engineering menu for some reason or you are uncomfortable with using the codes, there are alternative ways to check, and online services and specialized applications from Google Play can conduct similar tests with a more user-friendly interface and detailed statistics.
One of the most popular solutions is the Dead Pixel Test and Fix or Screen Test, which allows you to display clean colors, gradients and grids to check geometry, and the main advantage of such applications is the ability to leave the running test for a long time to warm up the matrix.
You can also use online services like DeadPixelBuddy or Monteon, and you just have to open your browser on your phone, go to the site, and run a test, which is convenient if you don't want to install unnecessary apps on your device.
- 📱 Dead Pixel Test and Fix: A powerful tool with the ability to try to restore stuck pixels.
- 🎨 Screen Test: a minimalist application specializing in color and gradient testing.
- 🌐 Online Monitor Test: Web version that does not require installation is suitable for quick check.
When using third-party apps, remember that they don’t have access to deep iron diagnostics like the engineering menu. They only display test images, so the final visual control is still on your shoulders.
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For the most accurate check with online services, turn on the Full-screen mode in the browser and turn off the autobrightness so that the screen light does not change during the test.
What to do if tests reveal problems
Detection of defects during inspection is unpleasant, but important information. Your next actions depend on the type of problem and the period of ownership of the device. If the phone is new (less than 14 days), you have the right to return it to the store or exchange it for a serviceable one, even if the defect is considered “acceptable” by the manufacturer, but interferes with you personally.
If the warranty is still valid but more than two weeks have passed, you need to fix the problem. Take screenshots (if the touchscreen allows) or take a video of the defect on another camera.
If the defect occurred after the warranty expired or is the result of mechanical impact (crack, impact), the repair will have to pay for yourself, in which case self-diagnosis helped you understand the scale of the problem and the estimated cost of recovery.
⚠️ Warning: When contacting a warranty service center, make sure to mention that you ran the tests through an engineering menu, which will show your technical literacy and confirm that the problem is hardware, not software.
Do not try to “treat” the screen with traditional methods, such as pressing or heating, if the device is warranty. Such actions can be regarded as an attempt to repair yourself, which will lead to a denial of warranty service.
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The presence of a video recording of the defect significantly accelerates the processors of the device in the service and reduces the likelihood of failure by the masters.