Buying a smartphone, especially from the hands or on popular marketplaces, always carries certain risks. The electronics market is full of replicas, restored devices and gadgets with replaced components that are seemingly indistinguishable from the original. Owners of Xiaomi, Redmi and POCO devices often face the need for a quick but deep check of the device’s condition to ensure its authenticity and technical health.
There are many ways to diagnose, from simple visual inspections to the use of hidden system utilities. Android’s engineering menu provides access to tests that are not normally available to the average user. In this article, we will discuss all the methods that will help you identify hidden defects, check the originality of the display, battery and other key nodes of your device.
Before you go into complex manipulations, it is important to understand that a comprehensive check takes time. You should not rely on just one test, as some components can be replaced with quality copies that easily pass basic check.
Authentication through MIUI and Google Services
The first and most obvious step is to verify the device through official channels. Xiaomi has implemented several layers of protection that distinguish the original gadget from the fake, but fraudsters have learned to cheat simple checks, so it is important to use a combination of methods.
The most reliable way to check the IMEI-This unique identifier is assigned to each communication module in production, and you can find it on a box, on a warranty card, or by typing the universal code *#06# in the Phone app. Compare the numbers you get with those on the back of the device (if it’s removable) and in the box.
⚠️ Attention: If IMEI-The code in the system does not match the number on the box, this is a sure sign that the smartphone has undergone serious repairs or is a “collection hodgepodge” from different devices.
Then you can use the manufacturer's official website, enter the serial number (S/N) and IMEI in a special form on the Xiaomi authentication portal, the system will instantly give the result: whether the model is confirmed, what its color and activation date, and check the availability of Google Play Protect services and the Google Play store, as cheap copies often have fake certificates.
📊 How to Check Your Smartphone Before Buying?
Visual examination
IMEI check
Test on the engineering menu
Computer-assisted verification
I don’t check, I buy in the official store.
The most powerful tool for testing hardware is the built-in engineering menu, known as the CIT (Customer Integration Test), a hidden part of the system designed for factory testers, but accessible to every user, where you can check the operation of each sensor, communication module and control without installing third-party software.
There are several ways to log in to the diagnostic menu. The easiest way is to open the Phone app and type a special command. Most devices with a MIUI or HyperOS shell run code ##6484##. If this code doesn't work, try the alternative ##64663##. Once you enter the last digit, the menu should open automatically.
The CIT interface is a checklist, and you pick any one, and you run a check, like the Touch Painter test, which checks the responsiveness of the screen, and Keypad, which checks the performance of all the buttons, and it's important to go through all the points consistently, especially if you're in doubt about the functionality of a particular component.
Some tests may require interaction, such as turning the phone when checking the accelerometer, and talking when testing the microphone, and if a test shows a Failed error, it indicates a hardware problem or driver failure, in which case a factory reset may help if the problem is software.
What do I do if the codes don't work?
On some global firmware versions or after a security update, access via USSD-codes can be limited to developers, in which case try to log in through the settings menu: go to Settings → The phone. → The kernel version and quickly click on this line 5-7 This action should also start the testing menu, and testing the display and touch layer of the screen is the most vulnerable and expensive element of the smartphone. When buying a used device, you can often encounter a replaced low-quality display that has poorer color reproduction or no protective oleophobic coating. In the engineering menu, select the test associated with the display (often called "Display" or "Display «LCD»). The screen will begin to cyclically change colors: red, green, blue, white and black. You shouldn't be interested in the dust under the glass, but look for broken pixels, points that are not the same color or not at all, and pay special attention to the touch layer test, which usually looks like a grid or an empty screen that you need to swipe your finger across. Your task is to draw lines in all directions without tearing your finger, and if the line is interrupted in a certain area or "shaking", this indicates a problem with the digitizer or plume. Checking parameter Normal condition Signs of defect Color rendering Saturated, uniform colors Dull colors, yellow, pink shade Brightness Smooth adjustment, high maximum Sharp jumps, low maximum brightness Touchscreen Lines drawn without breaks Touch skips, "phantom" Frequency of Update Flower Animation (60/90/120 Hz) Snatch, scroll delays Also worth checking the automatic brightness. Step out of the test menu, close the top of the screen (where the light sensor is located) and see if the screen goes out. If the sensor is flooded or faulty, the automatic adjustment will not work, which causes discomfort when using. Diagnostics of the battery battery State is a critical parameter for a used smartphone. Lithium polymer batteries degrade over time, losing capacity. Unlike the iPhone, there is no built-in simple percentage of battery health in the settings, but Xiaomi provides tools for assessing. In the CIT menu, find the section "Batter, if you need to change the temperature or the current status" it says "Hereater, or battery temperature." Also check the temperature in plain - it should not exceed 35-40 degrees Celsius. ⚠️ Warning: If the phone is quickly discharged or turned off when 15-20% And when you're charging, it's a sign of memory effect or battery cell degradation, even if the status on the menu is Good. USB In the "Developers" menu, connect the phone to your PC, and with the adb shell dumpsys batterystats command, you can get detailed discharge statistics, but for the average user, it is enough to observe the behavior of the device throughout the day. 40% straight away 10%) Checking cameras and multimedia modules Cameras in modern smartphones Xiaomi — complex optical systems. The check should include not only the presence of the image, but also the work of autofocus, stabilization and microphones. In the engineering menu there are separate tests for the Front Camera and Back Camera. Run the camera test and take several pictures of different objects: text close, landscape in the distance and the dark corner of the room. Notice the noise, the edge blur, and the speed of focus. If the camera prowls for a long time trying to focus, or makes a strange sound (rattles), the module may be damaged. OIS (Make sure you check the audio recording, record a short video while talking, and play it back, and then you can evaluate the main microphone and the speaker at the same time. CIT You can often have a Receiver test and a Speaker test -- you can do it. NFC. If you plan to use your phone for contactless payment, check it. In the test menu, select «NFC» If the phone doesn't respond, it's possible that the antenna module has unstuck or malfunctioned, and if you look at the memory and the processor under load, you can use system information to make sure that the device is the stuffing it claims to be, rather than the cheap ones. In the About Phone menu, click on the Kernel Version several times to open the details, or use third-party utilities like CPU-Z or AIDA64. Compare the SoC model to the official specification of your model. For example, the Redmi Note series often changed the processors in different revisions. Make sure that the number of cores and their frequency correspond to the stated (RAM) built-in (ROM). An imbalance in this data may indicate an overstuffed phone. To check the stability of work under load, you can run a heavy application or a game with high graphics on the computer. 10-15 Watch for body temperature and "freeze" (delays). If the phone is very warm in the upper part (where the processor) and starts to brake, perhaps the thermopaste has dried or the radiator press is broken. 💡Stable work under load and matching model characteristics are the main signs of a proper processor and cooling system (FAQ) How to check the originality of Xiaomi if the box is lost? Without the box, the main reference remains IMEI-The code in the system and on the case (if it is applied) compare it with the data on the official Xiaomi website. Also an indirect sign of originality is the operation of all Google services, the presence of the Mi logo when turned on and the build quality (no backlashes, gaps ##6484##? In newer versions of MIUI or HyperOS, and some global firmware, access to the engineering menu via dialing can be blocked for security reasons. Try alternative code ##64663## or log in via settings: Settings → Phone → Version of the kernel (multiple taps). Can you check the Xiaomi phone through your computer? Yes, by connecting the phone to the PC in debugging mode via USB, you can use programs like AIDA64 for PC or ADB console commands. This allows you to get more detailed information about the "calibre" and error logs than it shows on the phone's kernel (m) kernel (m, if you start with the battery status, but then you try it in the test, "What's up to the battery, if you first, if you turn on the battery, "Over in the test?" If the error persists, it is likely that the battery is physically worn out and needs to be replaced at the service center. Does flashing affect test results? Installing global firmware on the Chinese version or Custom ROM can change the display of certain parameters or block access to certain CIT sections. However, physical characteristics (matrix, processor, memory) will remain unchanged and can be verified through third-party utilities.