How to check your Xiaomi phone in boo: the full guide

Buying a used smartphone is always a lottery, especially when it comes to the popular Xiaomi brand.The market is full of offers where sellers swear that the device “collected dust in the closet”, although in fact it could work for months in difficult conditions. Visual inspection often does not give the full picture, as modern technology allows you to mask the traces of exploitation.

You should understand that hidden defects can manifest a week after purchase, when it will be impossible to return the money, so a comprehensive check of a gadget before transferring cash or confirming a transaction on an ad service is a mandatory ritual. In this article, we will discuss technical and software diagnostic methods.

Don't rely on the honesty of the seller. Even if the person looks very convincing, the technical data will tell the truth. Chinese brands have specific features of accounting for repairs and linking to accounts that not all users know about.

External examination and autopsy check

The first thing you get to grips with is the body of the device, and the microcracks on the screen or back can indicate falls that could have damaged the internal structure of the board, and you can look carefully at the joints of the body, and if you notice gaps or protruding edges, you've opened the phone.

Pay special attention to the screws near the charging port and speakers. On new devices or devices after the factory assembly, there should be no trace of unscrewing, if the screw hats are damaged or have scratches from the screwdriver, the phone was precisely dismantled.

• 🔍 Check the tray. SIM-maps: it should fit tightly and have a smooth color corresponding to the body.
• 🔍 Inspect the lenses of the cameras: inside the lenses should not be dust, condensation or traces of moisture.
• 🔍 Touch the screen when the display is turned off: it should be smooth, without chipping and “steps” on the edges.

⚠️ Warning: If the seller claims that the phone has never been opened, but you see traces of glue or irregularity on the edges, this is a sure sign of unqualified repair or replacement of the case.

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Bring a bright flashlight to the meeting, and the light at a sharp angle helps to reveal microscopic scratches on the screen and scuffs that are not visible in normal daylight.

The build quality is an indicator of the history of the device. If the volume or on buttons have a backlash or a crash, it indicates severe wear or impact. Mechanical damage often leads to problems with the contacts of the plumes in the future.

IMEI verification and device compliance

One of the most important steps is to reconcile identification numbers, and each smartphone has a unique IMEI (International Mobile Equipment Identity) that is stitched into the communication module, which must match the number on the box, the warranty card and the phone menu itself.

To find out the IMEI on the screen, use a universal code. Enter the following combination in the Phone app:

*#06#

Once you type in, the team automatically displays SIM card information and IDs, and if there are two slots in the phone, the IMEI numbers will be two, and they should match perfectly the ones printed on the factory sticker at the back of the box.

It's not superfluous to get this number through special services on the Internet, which will allow you to know whether the device is blacklisted by telecom operators as stolen or lost, and you can also determine the exact date of activation of the device, which will help you to understand the real age of the gadget.

IMEI matching is a basic guarantee that you are not looking at a "Frankenstein" piece of different parts. If the numbers don't match or appear as "Null/Unknown", you'd better drop out.

Diagnostics in the CIT engineering menu

The most reliable way to check Xiaomi’s technical status is by logging into the CIT (Customer Information Test) engineering menu, a built-in diagnostic tool available on all of the brand’s devices, which allows you to test each module separately.

Use the code to enter:

##6484##

Or go through settings: Settings → About Phone → All settings → The kernel version (you need to press 5-7 times) and the test list will open. You don't have to check everything, focus on the critical nodes.

In the Display, watch the broken pixels and the uniformity of the backlight. Press the screen to run the touchscreen test: swipe all zones, lines should be drawn without breaks, which is especially important for used technology, where there may be glass replacements.

Be sure to check the sensors. In the Proximity Sensor test, cover the top of the screen with your hand - it should go out. If the sensor doesn't work, you'll have your screen constantly turning on during a conversation and your cheek dropping calls.

⚠️ Attention: If on the menu CIT Some test items are missing or labeled as “Fail” even after a reboot, a sign of deep hardware malfunction or unoriginal parts.

Analysis of the battery status

Battery is the most rapidly degraded consumable. Android doesn't have a built-in simple "battery health" percentage like iOS, but you can get the data. Use a hidden menu or third-party utilities.

Enter the code in the dial menu:

##6485##

In the window open, find the parameters that start with MB_. You're interested in a line. MB_06 (Health -- it should say "Good." Also important is the line. MB_00 — current charge, and MF_02 — number of full charge cycles.

If the Cycle Count cycles are over 500-600, the battery life is significantly reduced, and if you're in active use, it will live half a day, and also pay attention to the physical condition: if the back cover is swollen or the screen is raised on one side, you can't use the battery.

For more detailed statistics, you can install an Ampere or AccuBattery app, and let it work for a couple of hours to get data on real capacity and wear rate, and that will help you bargain with the seller about the price cut.

Check for Mi Account and blocking

One of the biggest problems when buying used Xiaomi is binding to a Mi Cloud account. If the previous owner did not untie the device, you will get a “brick” that will not be fully used or reflashed.

Go to Settings → Mi Account. There should be no email addresses or phone numbers entered. If you have an account, request that you log out and remove the device from the trusted list.

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Never buy a phone if the seller says, “I’ll delete the account later,” or “I forgot the password, but the phone works.”

Also check the bootloader status, if it's unlocked, it means that the phone may have custom firmware, which increases the risk of unstable work, and you can find the status in the same CIT menu or in the development settings.

Make sure your device doesn't have an FRP lock, so after checking, ask the seller to reset the phone to the factory settings right in front of you, and when you turn it on, the phone will require you to enter the Google account that was on it before, and if the seller doesn't know the passwords, you have to cancel the deal.

Testing of cameras and communication modules

The cameras in today’s Xiaomi smartphones are complex and expensive to repair. Open the camera app and take some pictures in good light and in the dark. Take a close look at the photos: they should not be black spots (dust on the matrix) or blurred corners (lens shifting).

Turn on the video and walk around the room, and if it twitches or floats, then the optical stabilization (OIS) is faulty, and it's a common problem after falls, even if there's no external damage.

• 📞 Put it in. SIM-Map: Check if the network catches 4G/LTE Is the Internet working.
• 📶 Check Wi-Fi and Bluetooth modules: They should see networks and devices around.
• 📍 Launch navigation (GPS): coordinates should be determined 10-20 seconds in the open.

Check all the microphones. Turn on the recorder and talk with the bottom (main microphone), top (noise reduction) and front (video communication) clamped, the sound should be clean, without cracking or distortion.