How to check the screen of Xiaomi phone: full screen diagnostics

Modern Xiaomi smartphones are equipped with advanced AMOLED and IPS arrays that, when used carefully, last for years. However, even premium panels can suffer from manufacturing defects, mechanical damage or software failures that affect color reproduction and responsiveness. Screen diagnostics is the first step to be done when buying a used device or when you first suspect a malfunction.

The defects are not always visible to the naked eye when you use an interface as a standard, and microcracks, burnout of individual subpixels, or areas with impaired sensitivity can only occur under specific conditions, which is why it is important to know how to start the engineering mode and conduct a comprehensive check to eliminate hidden problems.

In this article, we will take a look at all the available testing methods, from built-in system tools to specialized applications, and learn how to distinguish software glitches from hardware breakdowns and understand when to carry a gadget to a service center, and when you can solve the problem yourself.

Visual Diagnostics and Search for Broken Pixels

The initial inspection always begins with a visual assessment of the image when the device is turned off and on. When the screen is turned off, carefully examine the surface under a bright light source: any scratches, chips or cracks can indicate potential problems with the touchscreen in the future, even if the matrix is intact.

Once the device is turned on, check for the uniformity of the backlight and the absence of broken or stuck pixels. A broken pixel is a point that constantly burns black, while a stuck one can burn red, green or blue. For quality checks, it is best to use monochromatic images.

• 🔴 Turn on a clean red background and carefully inspect all corners of the screen for black dots or spots of a different shade.
• 🟢 Switch to green and blue – this will help to identify defects of subpixels, characteristic of the color. OLED-matrix.
• ⚪ Display a pure white background to notice uneven backlighting (the “cloud” effect) or yellowness at the edges.
• ⚫ Include a black background in a dark room to check for “glow” corners or the presence of glowing dots.

If you find a single stuck pixel, don't jump to conclusions. Sometimes it helps to softly massage the screen (through a napkin) or use special videos that quickly change colors to "clip" the subpixel. However, if there are many defective dots or they are located heaped, this is a guarantee case.

⚠️ Warning: If you see bright rainbow spots or “oil” stains on a black background, this may indicate internal damage to the matrix or moisture entering the glass, even if the outer protective glass is intact.

Using the CIT Engineering Menu for Diagnostics

The most reliable and deepest way to check the screen of a Xiaomi phone is by using the built-in CIT (Customer Integration Test) engineering menu, which is a hidden section designed for factory testers and allows you to check every aspect of the equipment, including the touchpad and color gamut.

To enter the diagnostic menu, you need to open the standard Phone app and dial a special combination of characters, and after entering the code, the menu will open automatically, without having to press the call button.

##6484##

In the list that opens, you'll find the item that's associated with the display. Depending on the version of the MIUI or HyperOS firmware, it can be called Display, LCD, or Color. You click on it and you run a test that will consistently color the screen in different colors.

And you can also use the Touchpad, which is when you activate it, you get a grid or a black screen, and you're asked to swipe your finger all the lines, and if you don't register your finger in any area or the line is interrupted, you're insensitive.

Check the sensitivity of the touchscreen and Ghost Touch

One of the common problems with budget and some flagship Xiaomi models is the so-called “Ghost Touch” (fan taps), which is a phenomenon where the phone responds to touch, opens apps or prints text without the user’s input.

To check the uniformity of the sensor, you can use not only the engineering menu, but also special applications from Google Play, such as Touch Screen Test, which create a grid that you need to swipe your finger, fixing the gaps in the recording of touches.

The main signs of a faulty touch screen:

• 👆 The screen responds to late touches or requires re-pressing.
• 🌀 Spontaneous movements of the cursor or opening the menu without touching.
• 💥 «Dead zones where the screen does not respond to the finger.
• ⚡ Reaction to touch only with strong pressing.

Often the problem with phantom presses is not the hardware, but the bad grounding of the charger. If the Ghost Touch only appears while charging, try replacing the cable or power supply with the original one.

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If the screen is only behaving strangely in a case, remove it and check again.Cheap protective glass or thick cases can put pressure on the edges of the display, causing false positives.

Software tests and third-party applications

If built-in tools are not enough, specialized applications come to the rescue, allowing for more detailed analysis, including multi-touch testing (simultaneous recognition of multiple touches) and response time measurement.

One of the best tools is the TestM or Phone Check app, which is a comprehensive diagnostic of the entire device, but the screen test section is very convenient, and it will ask you to do a series of things: draw a figure, quickly tap on the corners, diagonally.

Also worth mentioning is the Dead Pixel Test and Fix app, which not only helps find defects, but also offers a feature to “cure” stuck pixels by quickly changing colors over time, and while the effectiveness of this method is controversial, it’s worth trying.

⚠️ Note: Do not use apps to “cure” broken pixels for too long (more than that). 10-15 Excessive loading on the matrix can lead to overheating and accelerated burnout.

Diagnostics of the plume and display connection

Sometimes the image problems (flickering, stripes, color changes) are not related to the matrix itself, but to the quality of the connection of the plume. If the phone recently fell or was hit, the connector inside could move away.

Symptoms of plume problems often occur when the body is bent or pressured on certain areas of the frame. If you press the top or bottom of the screen, the image distorts or fades, there is a high probability of poor contact.

What you can do on your own:

1. Carefully (without fanaticism) tap the screen frame in different places when the device is on.
2. Try to curve the phone slightly (very carefully!) while watching the reaction of the image.
3. Shake the device near your ear – if you hear a knock inside, the display module may have unstuck.

It is important to understand that soldering the plume or replacing the connector is a complex procedure that requires soldering equipment and skills. At home, it is better to limit yourself to diagnosis, and the repair is entrusted to professionals.

Comparative table of verification methods

For convenience, we systematize the methods we have examined, each of which has its own advantages and allows you to identify the type of defects.

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The combination of visual inspection and test via the #6484## engineering menu covers 95% of all possible screen defects without installing excess software.

Frequent Questions and Challenges (FAQ)