Modern Xiaomi smartphones are equipped with high quality AMOLED and IPS-Even flagship models are not immune to manufacturing defects or mechanical damage, and owners often face the need to check the matrix immediately after buying the device in a store or when receiving a parcel from a marketplace. This prevents problems with returning goods in the future.
There are several ways to do a deep screen diagnosis without a computer connection, and the most effective methods include using built-in engineering menus, special codes, and third-party apps to detect defects, and the most reliable way to check is to use the hidden CIT engineering menu available on all MIUI and HyperOS devices.
In this article, we will take a look at every step of testing, from visual inspection to color diagnostics software, and learn how to find broken pixels, detect uneven backlights, and check the touchscreen, which will help you objectively assess the screen quality of your Redmi or Poco.
Visual examination and primary diagnosis
Before you run complex software tests, you need to do a thorough visual inspection of the device, turn the screen on at maximum brightness and look at it carefully from different angles, look for cracks, chips or signs of layers of the matrix that may not be noticeable when the display is off.
Pay special attention to the uniformity of the glow. In monochromatic images (especially white and gray) often visible "clouds", yellow spots or dimming at the edges. This may indicate defects in the lighting or poor-quality module assembly. IPS-The screens are small, but for AMOLED The panels are a sign of marriage.
⚠️ Note: If you find physical damage (glass cracks or dents), software tests may not be available or show incorrect results due to a violation of the integrity of the plumes.
Also check the automatic brightness control. Close the light sensor with your finger - the screen should darken smoothly. Abrupt jumps in brightness or lack of response can indicate problems not only with the matrix, but also with the power controllers.
Using the CIT Engineering Menu for Tests
The most powerful diagnostic tool is the Customer Inspection Test (CIT) menu, which is built into the firmware of all Xiaomi smartphones and allows you to check each component separately. To get there, open the Phone app and type the combination ##6484##.
Once you enter the code, you'll see a list of tests, and you'll find the item associated with the display (usually called Display, Screen, or Color Bar), and you'll be able to switch between different colors to see if the test is successful.
☑️ Checking in CIT menu
It's important not just to look at colors, but to check the response of the touchscreen. The CIT menu often has a separate Touchpanel test, where you draw lines with your finger, and if lines break or appear elsewhere, the digitizer is damaged.
⚠️ Note: Do not press the Fail button unnecessarily, as this can write an error to the device’s log, which sometimes affects warranty cases when returning.
Diagnostics of broken pixels and color reproduction
Broken pixels are microscopic dots on a screen that don't change color or glow incorrectly, and can be "dead" (always black) or "burning" (constantly glowing white or color), and monochrome images are the best way to find them.
Turn on a completely black background in a dark room. If you see bright spots, they're burning pixels. Switch to a white background, the black dots indicate dead subpixels. Also check for red, green and blue separately, as the defect can only manifest in one of the RGB channels.
Sometimes the pixels are not completely dead, but simply stuck on a certain color, and unlike physical damage, such defects can sometimes be corrected by software-based "massaging" or video cycles that quickly change colors to make the crystals work.
Estimate the overall color reproduction. On AMOLED arrays, black should be absolutely deep, because the pixels in those zones are just off. If you see a gray glow across the field on a black background, maybe it's a brightness mode or a calibration feature.
Checking the uniformity of lighting and gradients
The uniformity of the glow is a critical parameter, especially for those who like to read from a phone or watch videos in the dark. To check, turn on a gray image (about 50% brightness), against which the brightness differences known as the "lantern effect" or clouding are best seen.
Nana IPS-Backlight bleed is often seen in the screens, and it's fine in small ways, but if one angle is clearly brighter than the other, it can interfere with comfort. AMOLED There should be no such problems in principle.
| Type of defect | It looks like | Criticism | Possibility of correction |
|---|---|---|---|
| Dead pixel | Black dot on any background | Low (if few) | Rarely (software) |
| Burning pixel | Bright colored dot | Medium | Possibly (warm-up/video) |
| The Light (Clouding) | Muddy spots on black | High (for AMOLED) | No (module replacement) |
| Yellow spot | Local color change | Tall. | No (organic degradation) |
Check the gradients, too. Turn on a black-to-white image. On a high-quality matrix, the transition should be smooth, without banding. The appearance of sharp steps indicates poor screen controller quality or poor calibration.
Testing of touch screen and multi-touch
The matrix is only half the success, the second part is the touchscreen, and even the perfect screen is useless if it doesn't respond to touch, and you can use the built-in test in the CIT menu to test the multitouch, or you can download an application like the MultiTouch Test.
In Touch Check mode, swipe your finger around the perimeter of the screen, the line should be continuous, without breaks in the corners and edges, and pay special attention to areas around the front camera and the dynamic island, if any.