Buying a new gadget is always an exciting moment, especially when it comes to popular brands such as Xiaomi, Redmi or POCO. The electronics market is full of offers, but at the same time, the risks of buying a restored device, a showcase sample or even an outright marriage that the seller is trying to pass off as a new product are growing.
You need to be very careful in the first minutes after receiving the box, because this is when most of the hidden defects can be detected, and ignoring the initial diagnosis often leads to long disputes with the store or the inability to return money if the problem manifests later.
In this guide, we will take a look at the algorithms that will help you protect yourself from a bad purchase, and we will look at the external features, software checks and hidden tests available in the MIUI or HyperOS shell.
External inspection and configuration check
The first thing you should do, before you turn the machine on, is to look carefully at the packaging. The original Xiaomi box is always made of dense cardboard with clear, high-quality logo and specification printing. Pay attention to the factory seals: they must be whole, without traces of gluing or damage.
Open the box and assess the condition of the device itself. The new smartphone should not have the slightest scratches, scuffs or screws unscrewed. Pay special attention to the USB-C charging connector and speaker: if you see dust or scuffs around the hole, this is a sure sign that the phone has already been used.
- 📦 Make sure that the serial numbers are on the box and on the sticker at the back of the case (or in the tray for SIM) match.
- 🔌 Check the build quality: swipe your finger at the joints of the body, there should be no gaps or backlash buttons anywhere.
- 🧩 The package should be complete: cable, paper clip, protective cover and documentation should be laid neatly, without traces of use.
⚠️ Warning: If you find micro-scratch marks around the screws or screwdriver marks on the bottom of the case, it means that the device was opened.
Also check the tray for SIM-In the new device, it should sit tightly, and its color should match perfectly the color of the case. If the tray is different in hue or dangling, perhaps the phone was dismantled to replace parts.
Initial start and screen check
After visual inspection, you can start turning on. Modern Xiaomi smartphones do not have to immediately show the desktop when they first start up, and you will be greeted by a welcome window with a choice of language, which indicates that the device has not been activated before.
The screen is the most expensive and fragile component. To check the matrix for broken pixels or uneven backlight, use built-in tools or just look closely at the white background. Turn on maximum brightness and look at the corners of the display.
So you have to pay special attention to the touchscreen, and you have to swipe across the screen, dragging the app icon, and it doesn't have to break off or stick in certain areas, and if you see areas where the sensor isn't responding, it's a marriage.
Check the proximity and light sensor. Hold your phone to your face while you simulate a bell: the screen should go out. Also check for autobrightness by covering the top of the screen with your palm.
- 🎨 Run a color image to make sure there are no spots ("clouding") and uniform color reproduction.
- 👆 Test multi-touch: Try pinching the screen with two, three or more fingers at the same time.
- 🔄 Check the refresh rate: if you have a 120Hz model, make sure the animations are smooth in the settings.
⚠️ Attention: AMOLED-This is a feature of the technology, but if the flicker is visible to the naked eye as a strong ripple, it can be a sign of a defect in the controller.
Be sure to check the front camera and speaker as soon as the system allows you to make a test call or video recording.
Diagnostics through CIT Engineering Menu
The most powerful tool to test is the Customer Interactive Test (CIT) mode, a hidden part of the system designed by Xiaomi engineers to test all the modules of the device before sale, and accessed through a special code.
To get to the menu, open the Phone app and type in the command ##6484##. If the code doesn't work, try going through the settings: Settings → About Phone → The kernel version (you need to press 5-7 times quickly).
##6484##In the list that opens, you'll see dozens of tests. You don't have to do all of them, but you need to do critical tests. Start by checking the vibrations, the volume and power buttons, and all the cameras.
Be sure to check the section associated with Touchpanel.There's often a line drawing test: swipe your finger all over the grid to make sure all the cells are stained.
- 🔊 Speaker test: the phone must play the melody, check the purity of the sound.
- 🎤 Microphone Test (Mic): Record your voice and listen to it, eliminating noises and wheezing.
- 📡 Wi-Fi and Bluetooth Test: Try to find the available networks and devices around.
IMEI and device status check
One of the most important steps is to verify the unique IMEI device identifier, which must match the box, phone settings and warranty card, and enter the code to display the IMEI on the screen via the command *#06#.
The resulting code can be checked on the manufacturer's official website or through authentication services, which will allow you to know whether the device is wanted and when it was first activated.
| Parameter | Where to look. | What to pay attention to |
|---|---|---|
| IMEI 1 | Setting up → The phone. | Matching the sticker on the box |
| Activation date | Must coincide with the date of purchase | |
| Guarantee | Service center / Website | Existence of current status |
| Region | Settings → About the phone | Global, CN, EEA (important for firmware) |
If the activation date on the site differs from the date of your purchase by several months, then the phone was activated earlier, most likely it is a showcase sample or a device that has been repaired.
It's also worth checking the region of the device. Global versions are intended for the global market. If you bought the Chinese version (CN) in the hope of global firmware, there may be problems with notifications and some applications.
Testing of communication modules and sensors
Communication quality is a critical parameter for any smartphone. SIM-map and check signal strength. → The phone. → All parameters can be seen signal level in dBm. -50 before -80 dBm is considered excellent, below -100 dBm is a weak signal.
Check the GPS and GLONASS modules. Open the maps and try to locate them. Indoor accuracy may be lower, but outside the smartphone should quickly find satellites. For detailed checks, you can use the GPS Test app.
Don't forget to test the NFC module if it's claimed. Try attaching your phone to your credit card or travel card. Also check the fingerprint scanner: it should respond quickly and the first time, even if your finger is slightly wet.
- 📶 Check Wi-Fi at 2.4 GHz and 5 GHz, the speed should correspond to the tariff.
- 📞 Make a test call to assess the noise reduction and volume of the interlocutor.
- 🔋 Track the discharge speed in standby mode for 15-20 minutes.
⚠️ Note: If the smartphone is very warm in the area of the camera or processor, even with simple actions (type text, menu), this may indicate problems with thermopaste or a defect in the motherboard.
Camera, sound and multimedia
The camera is one of the main arguments when buying Xiaomi: take some pictures in good light and with a lack of light. Pay attention to the speed of focus and the noise in the photo.
Check all lenses: primary, wide-angle and macro, switch between them without delays and application crashes, and test video recording, including stabilization.
The sound is checked not only through the speaker, but also through headphones. Insert wired headphones (if there is a connector) or plug in a Bluetooth headset. The sound should be clean, without cracking and wheezing at maximum volume.
Check the vibrator. Xiaomi's current models use a linear vibrator that gives a clear response. If the vibration is buzzing or too weak, it can be a sign of poor build quality.
Battery and productivity
The battery state of the new device should be perfect. Go to the settings and look at the flow statistics. If the phone is new, the graph should be almost empty and the battery wear should be 0% (although it is difficult to see software, the indirect sign is the charging speed).
Check the charging speed. Connect the original power supply and cable. Quick Charge animations (Power Delivery or proprietary Xiaomi Turbo Charge) should appear on the screen. If the phone is charging slowly, the cable or port may be damaged.
To test performance, you can run a heavy app or game. The phone should not freeze or slow down very much. In the Advanced Settings settings → Memory you can see free space.
- ⚡ Charging should start immediately after connecting the cable, without the need to plug the plug.
- 🌡️ The body temperature during fast charging can rise, but should not be burning.
- 📉 The phone should not lose more than one night. 2-3% charge.
⚠️ Warning: If the phone shows “Accessories not supported” when charging or charging is interrupted, the problem may be in the power controller or poor quality cable included in the kit.
Make sure that the amount of RAM and internal memory corresponds to the stated in the check. The real values are indicated in the About phone menu. Small discrepancies are permissible due to the number system, but a difference of 2 times (for example, 64 GB instead of 128 GB) indicates that the cheap counterpart is flashed over.