Choosing a “secondhand” phone helps users save a significant amount of money and use it for many other useful things. However, in order to buy a good quality, cheap used phone, many people wonder how to check it, because most of us often do not have much experience to evaluate the above parameters. machine. To help users gain more information and experience when choosing to buy used Samsung phones, the article below will guide users on how to test used devices before buying to avoid buying fake products. , goods are “boiled”, goods are built up.
Steps to check Samsung devices before buying include:
1. Check appearance
First, anyone who buys a used phone will first observe the sensory aspect of the product. Look carefully to see if the body and edges of the device are scratched or are there any serious scratches? The appearance of the device greatly determines the aesthetics, because no one will spend money to buy an old and ugly phone. Please check carefully because the device is not necessarily perfect, because the seller may replace the outer shell. So if you buy a phone that has been used for a few years and it feels as good as new, don't rush to secretly rejoice, remember to test more carefully in other steps to make sure you bought a good product. After checking, Appearance, if the machine meets the requirements, we will check the details inside the machine to see if it still works well?
2. Connection port
Charging port
This is a quite important part of the device. If the device cannot be charged, you will not be able to use it and will have to spend money to repair it. When testing the device, you should ask the user to charge it to see if the battery is working or not. In addition to plugging into the power source, you should also check the port connected to the computer to see if the computer receives it or not? Please look closely at the charging port, because used devices are often broken or have dust that is not guaranteed.
Headphone port
You should also try plugging the headset into the device to see if the headset works well, if the sound is muffled or if there are any errors.
3. Use the test machine command to check the hardware
For Samsung models, you can use the command *#0*# to check the device's hardware. After entering the command, the machine test interface appears, select each item to test the product.
- Check the screen: Select Red, Green, Blue, Dimming.
- Touch test: Touch.
- Check speakers: Receiver, Speaker.
- Vibration test: Vibration.
- Check camera: Front cam, Mega cam.
- Check function keys: Sub key.
- Along with many other feature tests. These are the main inspection items you can refer to.
In addition, you can also use some of the following codes to check additional information for the device:
- Software version check code: *#9999#.
- Vibration test code: *#9998*842#.
- Code to check battery operating parameters: *#9998 *228#.
- Code to change menu to English: *#0001# and press SEND.
4. You check the connections and sensors
Wifi connection
Connect the device to wifi to see if the device has any errors. Open the applications and browsers on the phone to see if the device is connecting to wifi or not?
Bluetooth connection
Send files via Bluetooth to other devices as well as receive from other devices to see if others can find you when connected to Bluetooth.
Sensor automatically rotates the screen
While watching a movie, turn on the automatic screen rotation mode on your device to see if this feature is still sensitive or not.
Proximity sensor
When you make a phone call and cover the sensor with your hand, if the screen is turned off, the proximity sensor will still work well.
GPS location positioning activity
Go to the Google Map application to see if the device is positioned relatively accurately at the location where you are opening the device. If you get a relatively accurate location, you can safely use the positioning feature on your device.
So the device can partly reflect the quality of the hardware and software running on the device.
Take photos, record videos
Many people are very interested in this feature, so please open the camera and check to see if the image quality is good and sharp?
5. Related accounts
When buying a used device, you need to ask the seller to log out of all available accounts on the device such as Samsung account and Google account. Because if you don't log out, your phone can easily fall into a locked state. So, please log out of the old owner's account and restore the device's factory settings to ensure safety when using.
6. Check your device's IMEI
Each of us will possess a different DNA sample, and smartphones are the same. The IMEI number of mobile phones can be viewed as a piece of DNA code. You will never find two phones with identical IMEI numbers, unless one of those two phones has a problem. Therefore, when buying a used phone, you should carefully check the IMEI number.
To check your device's IMEI number, enter *#06#. At this point, a window will open that will display information about the device's IMEI number.
Next, compare this IMEI number with its own IMEI number on the phone's Settings section to see if they match. Some phone models have the IMEI number printed on the back (eg iPhone) or have a sticker printed on the IMEI below the battery of the device. Please compare with the IMEI numbers in these locations.
If all IMEI numbers match, your phone has passed the “parking round”. If there is any difference, it is an abnormal manifestation. It's very possible that the phone you're testing has had its motherboard swapped or its IMEI number changed, for example.
7. Run these 2 tests before buying a used Samsung phone!
The appeal of used Samsung phones is undeniable: Top specs at a fraction of the price. However, with used devices, there is a risk of potential problems, and it's important to thoroughly inspect a used Samsung phone to avoid costly surprises later.
Use One UI's secret hardware diagnostics menu
One of the best ways to assess the condition of a used Samsung phone is to use the secret hardware diagnostics menu in One UI. This menu allows you to run tests on essential hardware components, helping you check for potential issues with the display, sensors, touch inputs, speakers, etc.
To access this menu, simply open the application Phone on your Galaxy device and enter *#0*#. When the diagnostics menu appears, you can perform individual tests to evaluate the health of your device. Some of these tests are interactive, requiring you to follow on-screen instructions, while others are quick and easy to verify.
For example, click on options Vibration will activate your phone's vibration motor, allowing you to confirm that it's working as expected. If select option Touchyou'll need to draw a line through a series of boxes to test the touchscreen's responsiveness and accuracy.

Running these tests will help identify potential errors or glitches, such as an unresponsive touchscreen, faulty sensors, or audio problems, that could affect your overall experience .
If any problems arise during the inspection, it's best to reconsider the purchase or negotiate a discount with the seller to cover potential repairs.
Run phone diagnostics using the Samsung Members app
While One UI's built-in diagnostics menu is a great starting point for assessing the health of your Samsung phone, it's not comprehensive. What if you buy a device only to later discover that the device's battery health has significantly decreased, the fingerprint sensor is malfunctioning, or worse yet, the device has cellular network problems?
With the Samsung Members app, you can check your phone's most important hardware and software components. This app lets you test everything from NFC, Bluetooth and microphone to more practical features like charging cables, cameras and speakers.
- Open the Samsung Members app on your Galaxy phone. If you can't find it, download it from the Play Store.
- Go to tab Support in the lower right corner.
- Select Phone diagnostics.
- Click the button Test all to begin a full diagnostic test of the device.

Again, some of these tests will require you to interact. For example, you may be prompted to press specific buttons to evaluate their responsiveness or listen to sound samples to evaluate the speaker's performance. However, you should be able to complete all the tests in just a few minutes.
Wishing you the best and wisest decisions.
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