How to check Xiaomi when buying from hand: a complete guide to diagnosis

Buying a Xiaomi smartphone from hand is a great way to save money by getting flagship performance at the price of a budget. However, the market for used equipment is full of refurbished devices, “bricks” with an unlocked bootloader and devices after poor-quality repairs. Unlike buying in an official store, here you risk running into hidden defects that will surface after a week of use.

Checking Redmi or POCO requires not only the look and feel, but also the software, and the statistics from service centers show that more than 30 percent of problem devices are sold because of hidden software locks or a cheap display, and your job is to identify these nuances before you transfer money.

In this article, we will discuss a step-by-step algorithm that will help weed out problematic gadgets. We will use hidden engineering menus, IMEI verification and visual inspection to verify the authenticity and health of the device. Follow the instructions to make the purchase successful.

Visual inspection and inspection of the hull

The first impression is often misleading, but that's where all the examinations begin: Take the phone in your hands and look carefully at the junctions of the case and the frame. Any gaps, even microscopic ones, can indicate that the device has been opened. This is critical, because after opening, moisture protection is often lost (if claimed) and the plumes can be damaged.

Pay special attention to the screws near the charging port and speakers. Torn slats or scratches around them are a sure sign of unskilled interference. If the seller claims that the phone has never been opened and the screws look like they were picked with a screwdriver, you better refuse the deal.

Check the glass conditions of the cameras, they should not be dusted inside or outside, the presence of dust under the lenses means a leakage disorder, which in the future will lead to fogging and failure of the module, and also inspect the charging connector: it should sit tight, without backlashes and oxidation of contacts.

⚠️ WARNING: If you see "bubbles" of peeling glass or rainbow spots on the edges of the display, this is a sign that the screen was changed in artisanal conditions, most likely using a cheap analog instead of the original.

IMEI and Block Status Check

One of the most important steps is to verify the unique device ID. Type *#06# on the dial keyboard. IMEI. Compare them with those on the box (if any) and the sticker in the tray. SIM-maps (on older models) or in system settings.

Disparate numbers are a red flag, which could mean that the phone has a motherboard from another device or it was assembled from multiple donors. Also check the status of locks through special services on IMEI. This is especially true for Xiaomi devices because of the Mi Account system.

Make sure that the device does not hang someone else's Mi Account. The seller should log out of your Google and Mi Account with you, and then perform a full reset. If the seller refuses to reset the phone, claiming that "there is everything set up", this is a reason to be wary.

Diagnostics of the display and touch screen

The screen is the most expensive and fragile element of a smartphone. To check the matrix, Xiaomi has a built-in engineering menu. Open the Phone app and type ##6484#. You will be taken to the CIT (Customer Information Test) menu. Select the item associated with the display check (usually called Display or Color Test).

The screen will be consistently painted in different colors. Carefully look for broken pixels (light spots), uneven backlights (lights) or “yellow spots.” Especially carefully check for white and gray colors, which are the best visible defects.

Then go to the Touch test, and you'll have to swipe all the lines on the screen, and the dead zones where the line is interrupted or not drawn, indicate that the digitizer is malfunctioning.

⚠️ Note: If the touchscreen is checked, the lines are drawn in jerks or “shake” without your participation, it is possible that the display is of poor quality (copy) or the plume is damaged.

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The engineering menu also checks the vibration and operation of all the buttons. Don't ignore the volume test - a quiet or wheezing speaker is difficult to replace in some Redmi models.

Testing of cameras and multimedia

Cameras are the second most important element after the screen. Run a standard camera app and take some pictures in good light and in the dark. Pay attention to the focus: it must be fast and accurate. If the camera is long to prowl trying to catch the focus, it may be worn out or damaged.

Check all the lenses, wide-angle, telephoto and macro. Switch between them and take pictures. Also record a video of the sound to check the microphones. Swipe your finger down the bottom of the screen while recording — if the sound is interrupted, then the noise cancellation or microphone is not working properly.

Remember to check the front camera and the flash. The flash should light up instantly and burn smoothly, without blinking. To check the speakers, turn on any music at maximum volume - the sound should be clear, without wheezing or rattling.

Checking the battery and charging system

Battery status is a key factor in the durability of a used smartphone. In the CIT menu (#6484##), find Battery or Status, which shows the current charge, voltage and, most importantly, the number of charge cycles (Cycle Count).

If the charging cycles are more than 500-600, the battery has already lost a significant part of its capacity. Also note the Health option if it is available in your version of MIUI/HyperOS. A value below 80% indicates the need for an early replacement.

Make sure to plug in the charger. The phone needs to respond instantly. If the charge is jerky (the icon appears, it disappears), the problem may be the connector or the power controller, and also check if the device warms up in the camera or battery area when fast charging.

Checking communications, Wi-Fi and sensors

A smartphone should not only play games, but also call. SIM-You can check the signal level, and you can call someone and talk for a few minutes with your phone in your hand, and you can check the main microphone and speaker.

Turn on Wi-Fi and Bluetooth. Try connecting to an accessible network and transferring a file. If the phone "sees" the network but doesn't connect, or the connection is permanently cut off, the problem may be in the antenna module. This is a common problem after falls.

Check the sensors. There's a Sensor test on the CIT menu. Shake your phone (accelometer check), put it to your face (approach sensor should turn off the screen), and check for autobrightness. A faulty proximity sensor is a scourge of many Xiaomi models that makes calls uncomfortable.

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If a test is marked in red (Fail) in the engineering menu, this means a hardware fault of the component that cannot be fixed software.

Frequently Asked Questions (FAQ)