Buying a new smartphone, especially from a popular brand like Xiaomi, always comes with the risk of an unscrupulous seller or a hidden manufacturing defect. The electronics market is crowded with refurbished devices, so-called refurbished models that are issued as new ones, as well as high-quality copies. Which is why the procedure of thoroughly checking the gadget in the store or when you meet a courier becomes critical to saving your money and nerves.
The diagnostic process takes no more than 15-20 minutes, but allows you to weed out up to 90% of potentially problematic devices. You do not need to be an engineer or have special tools, since the MIUI and HyperOS shell already have powerful engineering menus for self-diagnosis built in, the main thing is to know where to click and which parameters to pay close attention to first.
Ignoring the initial inspection often leads to unpleasant surprises after the return period has expired within 14 days. Dead pixels, a burnt-out screen, a non-original battery or a device locked in the region are just the tip of the iceberg of problems that can be avoided. Let's take a step-by-step algorithm that will save you from buying a "cat in a bag."
Visual inspection of the body and configuration
The first thing that starts with checking any device is a detailed external inspection. Even if the phone is sealed in factory film, pay attention to the quality of the printing box, the clarity of the barcodes and the presence of holograms. There should be no trace of opening or re-sticking stickers on the ends of the package. Xiaomi's original packaging is always made of dense cardboard with perfect face-to-face docking.
Remove the smartphone and study it carefully in good light, preferably using the flashlight of another phone. Run your finger along the joints of the case: they should be smooth, without gaps and sharp barbs. Pay special attention to the USB-C charging connector and speaker - they should not be the slightest dust or scratches from the plug, because even one connection leaves microtraces.
⚠️ WARNING: If you find scuffs on the edges, micro scratches on the camera lens or traces of screws unscrewing near the charging connector, this is a sure sign that the device was in use or opened.
Check the components: charging cable, SIM tray clip and documentation. Xiaomi cable usually has a brand logo and a quality braid or smooth matte coating. Cheap plastic, smell of chemistry or lack of marking on accessories can indicate an unoriginal configuration, which is often found in so-called "unpacked" versions.
☑️ Primary examination
IMEI authentication and serial number
One of the most reliable ways to make sure that you are not a stolen or cloned device is to reconcile IDs. Each smartphone has a unique IMEI code that is written in hardware and duplicated on the box. For quick checks, type the universal command *#06# in the app.
On the screen will appear information about two slots SIM (If the model supports two cards, and possibly a code MEID. These numbers should be one in one with those printed on the sticker behind the box and on the label under the tray. SIM-If the numbers are different or the phone shows «Null/Unknown», You have either a deep flashing, or a machine with a replaced motherboard.
Then you need to break through the device through official services. Go to the Xiaomi warranty check site or use third-party but reliable databases. By entering the serial number SN, you will know the date of activation of the device and the status of the warranty. If the phone is supposedly new, but the warranty on it expired six months ago, it is a restored device or ref.
What is IMEI and why is it needed?
It is also important to check the status of the lock by region: some models designed for the Chinese market (CN Version) may have software restrictions or no Russian languages in the box, although they may appear on the menu after firmware.
Diagnostics of the display and sensor through the engineering menu
The screen is the most expensive and fragile element of the smartphone. To check it for broken pixels, uneven backlights (“lights”) and color quality, the best way to use the built-in test is to enter the code ##64663## in the call or go to Settings → About Phone → Version of the kernel (click 5-7 times) to get into the CIT menu.
In the test list, select the item associated with the display (usually called Display or Color Bar). The screen will be consistently painted in red, green, blue, white and black. Carefully look at the uniformity: there should be no dark spots, pink shades in the corners or flickering. Black on AMOLED-The screens should be completely black, without gray plaque.
| Type of defect | It looks like | Criticism |
|---|---|---|
| A broken pixel | A point that does not change color (black or color) | Tall (observable to the eye) |
| Light. | A bright spot on a black background | Medium (noticeably in the dark) |
| Touch-glut | Spontaneous pressing or ignoring touching | Critical (unable to use) |
| yellowness | Uneven shade at the edges of the screen | Low (often a feature of the matrix) |
After checking the colors, be sure to test the sensor. In the CIT menu, select Touchpanel and swipe across the screen, drawing lines. They should be flat, without tears and tremors. Pay special attention to the edges, areas where there are often problems with multi-touch, if the line is interrupted or twitched, the sensor does not work properly.
Testing of cameras, sound and microphones
Many shoppers forget to check the cameras before payment, and at home they find that the photos are cloudy or the video is not written. Run the standard Camera app and take some pictures in good light and then in low light. Pay attention to the focus speed: it should be instantaneous, without scouring the lens.
Switch to the front camera and check all the modules: wide-angle, telephoto and macro. Video should be recorded in maximum resolution (for example, 4K 60fps, if supported) and listen to the sound. Image stabilization should work smoothly, without jerking when walking. Also check the flash in flash mode - it should not blink or go out.
⚠️ Warning: Be sure to check all the microphones. The main one is on the bottom, the second one is on top or back, the third one is often in the headset jack or on the end. Record the dictaphone note by clamping different parts of the body to make sure that the sound is written from all sides and there are no wheezing. To check the speakers, turn on the music at maximum volume. The sound should be clean, without cracking, squeezing the body and "crowding" sounds at low frequencies. CIT And there's also the Speaker and Receiver test, which play tunes through the spoken and the main speakers, respectively. Battery and cooling analysis is a key parameter, especially if you're not buying a phone from a store. CIT Find the Battery test, and it shows the current charge, voltage, and status. However, more accurate information can be obtained by installing an application like Ampere or AccuBattery (if you can install it). APK). Xiaomi’s original battery should not heat up higher when charging 40-42 If the phone is warm out of the box or warmed in standby mode, that's a bad sign. Also, pay attention to the charging speed: plug in the original power supply and see if the Quick Charge logo is activated, PD, HyperCharge). 💡If the phone shows 0% Lithium batteries can go into deep discharge with prolonged storage. 15-20 Check the vibrator. Xiaomi's modern smartphones use a linear vibrator that gives a clear, short response, not a long jitter. In the settings or vibration test (Vibrator), evaluate the nature of the response: it should be pleasant and tactile, without any extraneous rattling inside the case. Testing sensors and communication modules. SIM-Check the level of reception of the signal, it should be stable, without constant jumps from the 4G ce 3G And back in the safe zone. Be sure to check the Wi-Fi: the phone should see the 2.4 and 5 GHz networks, and the connection speed should match your tariff. NFC, If you want to see it, try putting it on your credit card or your travel card, and it's going to sound like a sound or a vibration. GPS: You can run the maps and locate them, and the accuracy of the positioning indoors and outdoors should be very good. Remember the proximity and light sensor. When you make a test call, close the top of the screen with your palm, the screen should go out, and when you move your hand away, it should catch fire. If the screen doesn't go out or goes out on its own during a conversation, the sensor is defective or contaminated. 💡Comprehensive inspection of all sensors, communications and NFC It only takes 5 minutes, but ensures you don't buy a phone with a broken module, which can cost up to 30% of the price of the device.Frequently asked questions (FAQ) Can Xiaomi be tested for originality just by appearance? No, appearance is just the first step. Modern replicas can look one-on-one like the original, including weight and materials. IMEI, serial number on the official website and testing through the engineering menu CIT guarantee of authenticity. What to do if it's on the menu CIT Some tests are marked in red (Fail)? If the test is marked as Fail, it means a hardware or software error of the corresponding module. For a new phone, this is unacceptable. If you are in a store, demand a replacement device. If at home, file a refund, because this is a manufacturing defect. How to distinguish Global Version from Chinese Version (CN)? Global Version has a box with the inscription “Global Version”, the European charger plug (or adapter) is included in the kit, Google Play is preinstalled and the Russian language out of the box is preinstalled. CN-The version may not have Russian in the basic firmware and requires firmware reflashing. Is it true that the code ##64663## works on all Xiaomi? POCO shelled MIUI HyperOS. However, on some custom firmware or heavily modified versions for specific regions, access to the menu may be limited. Should you buy Xiaomi if the warranty is already activated? Buying a device with an activated warranty is only permissible if you buy it as an "Open Box" (used or showcase sample) at a significant discount. For a new phone, the warranty activation date should coincide with the date of your purchase or be in the future.