What should you check before buying a used phone?

If you buy a used phone from an unknown person, or even from a known person, you must always check the phone for any damage - visible or hidden. But what all needs to be checked? How? That is exactly what I am writing in this article!

Note: I only write about original phones, not replicas.

It would be good to equip yourself a little before you start testing the phone, so I recommend that you bring, for example:

• External battery
• Passive NFC tags (if the phone has NFC)
• A lamp (or phone with LED flash)
• Maybe a magnifying glass if you can't see well
• Wireless charger (if your phone has wireless charging)
• Your own and spare SIM card
• Memory card

1. Visual inspection

First of all, check for physical damage, unless you don't mind. If the ad says there are no traces of use, check it out. If the seller lied about it, who knows what else he will do. So, visual inspection in the first place.

2. Is everything original

Be sure to check that the phone itself is original by looking for the IMEI on the box and in the phone information: Settings > about the phone. Once you're there, check the exact model designation (e.g. H815 for LG G4) and look it up on the Internet to see if it throws out the name of the original phone or replica.

Also, make sure that all the equipment is genuine, especially the battery. If you cannot open the back panel of the phone, download the Battery health application to the phone. It will serve as a GSam Battery Monitor

Then in the headphone box, the charger and USB cable. There are various ways to determine if the equipment is a copy, and a safe way is if you read where it was produced, and you feel very poor quality material. It often happens that the parts are not well assembled, so you can see the gap and the like.

3. Is charging

Bring a power bank (if the meeting place is somewhere outside) and simply check if the phone is charging when you turn it on. Also, if your phone has wireless charging capability, bring a wireless charger (you can connect it to an external battery).

4. Check SIM and SD slots

Insert your SIM and SD card (if there is a slot) clean to check if the phone will work on your network, and if the slots are damaged, ie. that you will not accidentally accept SIM and/or SD cards.

Then be sure to try to call a number (eg the backup SIM you brought), send and receive an SMS, copy something to the SD card, etc.

5. Is the phone wet

When inserting the SIM card, check the pink sticker for stains. Each phone has a small indicator that is white and has pink crosses. As soon as the phone comes in contact with water, that sticker turns completely pink (smears the color of the cross). This sticker is located somewhere under the back cover if the battery can be changed, or somewhere in the SIM card slot (or in another slot/connector) hidden so that it is barely visible. It would be best to point the lamp (LED flash of another phone, for example) and look for that sticker.

6. Does the internet work?

Be sure to check both WiFi and mobile network. Try loading google.com over WiFi and mobile. If you inserted your SIM card and don't have megabytes, sacrifice a dinar of credit and load google that weighs a few KB.

7. Service codes

There is a universal service code for each phone with which you can check the LCD, vibration, touch, and other important functions of the phone. This is the code: *#0*#

Enter it by opening the calling application and entering this code and "calling" it (ie tapping on the handset). Now you have several tests and choose each one in turn.

In addition, each phone manufacturer adds some additional codes, and you can find a list of those codes in the article I wrote - LINK.

8. Check sensor and function

And now manually check everything: microphone, vibration, sound, FM radio, BT, GPS, WiFi, 4G / 3G, proximity, fingerprint, light sensor, rotation, gyro, accelerometer, LED flashlight, NFC, WiFi hotspot, notif LED … It depends on which phone has what sensor, some have a barometer, temperature meter, heart rate, etc. You should know this before buying a phone, so check it all out.

9. Headphones

Make sure that, first of all, the headphones are original. Then do they work? Insert them into the headphone jack and play some music. Increase to the end and reduce. Test the keys on the headphones and the microphone. Are there any interruptions if you move the cable a little.

10. Camera

Be sure to check the camera, first visually from the outside and then through software. Take a few pictures and see that some stains do not appear by accident (it happens if dirt gets into the camera). You know what the camera is like on the phone you are buying and how capable it is, so make sure it has everything you need. For example. test OIS if possessed.

11. Reboot

In the end, simply restart the phone to see if everything is ok so that there are no surprises during or after turning on the phone.

Additional tips:

• Make sure you meet during the day in a public place where there are people (you know what kind of country we live in)
• Check the warranty is valid (if any)
• Use instinct. You know best what to do and check when you see the person and the phone itself