Buying a new gadget from the Chinese giant is always a lottery, especially if you are considering the market for used devices or ordering from abroad. Xiaomi is famous for its value for money, but it is the popularity of the brand that has spawned a huge number of fakes and restored copies, issued as new.
In this article, we will discuss in detail the algorithm of actions that will allow you to identify hidden problems before paying for the goods. You should not rely only on the appearance of the box or the assurance of the seller, because modern methods of repackaging and flashing make visual assessment insufficient. Careful diagnosis is the only way to protect your finances.
You'll need about 15-20 minutes of free time and a charged smartphone to run some tests, and we'll look at both software testing methods through hidden engineering menus and physical inspection of the case and components, and this guide is relevant for all series, including Redmi and POCO.
Primary visual inspection and configuration
The first thing that any inspection starts with is packaging. The original Xiaomi box is always made of dense cardboard with clear, bright printing. Pay attention to the quality of printing barcodes and logos: on fakes, letters often "float" and colors look dull or overly saturated. At the bottom of the box, a sticker with a serial number, IMEI and a model of the device should match the data on the back cover of the smartphone.
Carefully inspect the device itself in good lighting. Even if the device is sold as new, it may have micro scratches or traces of screws unscrewing near the connectors. Pay special attention to the joints of the case and the screen frame: gaps should be minimal and uniform throughout the perimeter. If you feel a backlash or see glue protruding from under the glass, this is a sure sign of poor-quality assembly or artisanal repairs.
⚠️ Warning: If a vendor claims that the smartphone “opened to install the Russian language”, know that global versions of Xiaomi already have Russification out of the box.
The kit can also tell a lot. The original kit always has a USB-C cable (unless the model is very old), a SIM extraction paperclip and documentation. The charger must have a clear power marking and brand logo. Check the plastic quality of the plugs and wires: the originals are always monolithic, without burrs and the smell of cheap plastic.
☑️ Primary examination
Authentication through IMEI and serial number
One of the most reliable ways to distinguish the original from the copy is to check the unique device ID. IMEI (International Mobile Equipment Identity) is a digital passport of your phone that is sewn in the factory and should not be changed, you can find it on the sticker of the box, under the battery (if it is removable), or by typing the universal code *#06# in the Phone app.
The resulting code must be checked against the manufacturer's official website. Go to the Xiaomi authentication page and enter the serial number or IMEI. The system will give the exact model of the device, the date of activation and the warranty status. If the site says "such a number is not found" or shows a model different from the one in your hands (for example, instead of the Redmi Note 10, the Mi 8 is displayed), you are either a fake or a device with broken IDs.
Also worth noting is the output format of the code input: on original MIUI or HyperOS devices, the system response comes instantly and structured. On Chinese copies with a redrawn interface, this code may not work at all or give an error, since it has a stripped-down version of Android that masquerades as a Xiaomi shell.
What to do if IMEI is interrupted?
Diagnostics of the display and touch screen
The screen is the most expensive and fragile part of the smartphone. When you buy a used device, you often find replaced low-quality displays. First of all, turn the screen on at maximum brightness and open the white image. There should be no yellow spots, no clouds, no dark corners. OLED-matrix (AMOLED) black color should be absolutely black, without gray glow.
There is a special test to check the touchscreen (touch layer) in the Xiaomi engineering menu, but you can also do a visual test: open the app icon and hold it all over the screen, pressed to the surface. If the icon “sticks” or twitches in certain areas without your participation, then in these places the touch layer is damaged or degraded.
Separately, check the multi-touch. Many modern models support 10 simultaneous touches. Hold the screen with a few fingers and try to move them. If the phone responds to all touches correctly, the controller is fine. Also note the presence of an oleophobic coating: swipe your finger across the screen; if the finger slides easily and the tracks disappear quickly, the coating is in place. If the screen is “rusty” and greasy marks remain forever, this is a sign of a cheap copy or a very budget glass.
| Type of matrix | Features of the inspection | Frequent defects |
|---|---|---|
| IPS | Corner screening | Fading, uneven lighting |
| AMOLED | Checking black (must be extinguished) | Static element burnout, flickering (PWM) |
| TFT | Verification of viewing angles | Inversion of colors at an angle, low brightness |
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To quickly check for broken pixels, run a video with pure colors (red, green, blue, white, black) on YouTube in full-screen mode. Any dot that differs in color from the background is a defect.
Battery testing and charging system
Battery status is a critical parameter when buying a used smartphone. Visually assessing the wear of a Li-Pol or Li-Ion cell is difficult, but indirect signs will help to understand the real picture. Turn on the phone and immediately see the percentage of charge. If the device was on the shelf for a long time, the charge could fall, but it should not be zero. A sharp jump in charge (for example, from 20% to 80% per minute of charging or vice versa, fast discharge) indicates a malfunction of the controller or the battery itself.
On the engineering menu ##6485## (It works on many, but not all, models, and you can find information about the charging cycles. MB_06 (Cycle count: if the number of cycles is close to 0, And the phone is sold as a used one, and it's a reason to wonder if the battery was ever exchanged for a cheap one. 10-15), As the factory is testing.
Make sure to check the charging connector. Insert the USB cable and swing it from side to side. Charging should not be lost at the slightest movement. Also check the charging speed: plug in the original power supply (or powerful analogue) and see if the Quick Charge (Power Delivery) sign appears. If the phone charges slowly even from a powerful unit, the problem may be in the cable, connector or power controller inside the device.
Checking cameras, microphones and speakers
Multimedia is something that Xiaomi likes to do. Camera checks should be comprehensive. Run a standard app and take a few shots in good light and then in the dark. Pay attention to focus: point the camera at text or a small object and tap your finger on the screen at different points. Autofocus should work quickly and clearly. If the camera is "sniffing" or emits a mechanical crack, the module is faulty.
Video recording is a great test for stabilization and microphones. Turn on video recording in 4K (if supported) or 1080p and walk around the room, talking into the microphone. The video should be smooth, without jerks, and the sound should be clear, without wheezing or interrupting. Be sure to check the noise reduction: holding your hand against the bottom end (where the microphone is usually), you should hear the change in the nature of the sound or see the indication on the screen.
Speakers are checked by playing music at maximum volume. The sound should be clean, without rattling the body and wheezing. In stereo, check both channels: the upper (auditory) and the lower. If one is silent or sounds deaf, the speaker may be flooded or damaged. Also, be sure to check the vibrator motor: it should be palpable, but not "rattle".
⚠️ Warning: When testing the camera, be sure to check all lenses (width, macro, TV). Often sellers hide non-working additional modules using software plugs.
Engineering menu and processor stress test
The final test is load testing. The hidden menu ##6484## (CIT) provides access to all sensors and modules. Go through the list: check the accelerometer (turns of the screen), the proximity sensor (close the top of the screen with your hand - it should go out), the compass and GPS. If GPS can't catch satellites outdoors for a long time, the antenna module may be damaged.
To check the processor and cooling system, it is better to install a third-party application, such as the Throttling Test CPU or Geekbench. Run the test and watch the temperature and frequencies. If the phone heats up to an uncomfortable 45-50 degrees in a couple of minutes or the frequencies drop sharply (trottling) long before the test is over, the cooling system can be ineffective or thermal contact is disrupted.
Also, during the stress test, monitor the behavior of the interface. Lags, getting stuck or sudden reboots under load indicate memory problems or software instability. Stable work under load is a guarantee that the phone will last a long time without surprises.
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Successful passage of the stress test for 10-15 minutes without overheating and resets is a guarantee of serviceability of the main filling of the smartphone.