Buying a used smartphone is a great way to save 30–50% off the price of a new device and still get a flagship from the previous generation. But such a deal also has a downside: hidden defects, locked devices, "water-damaged" phones, and fakes. To avoid disappointment, you need to know what to look for. We've prepared a checklist of 12 essential checks — go through it before handing over your money.
1. Check IMEI and serial number
Dial *#06# — the IMEI will appear on the screen. Compare it with the number on the box, in the settings ("About Phone"), and on the SIM card tray. All three values must match. Then, "check" the IMEI on the manufacturer's website (e.g., checkcoverage.apple.com for iPhone) or through services like imei.info — this will tell you the model, year of manufacture, warranty status, and whether the device is reported stolen.
2. Make sure it's not an iCloud/Google lock
The main headache of the used market is locked devices. Ask the seller to log out of their Apple ID or Google account right in front of you and perform a factory reset. After the reset, the phone should go through the initial setup without asking for someone else's password. If the seller refuses, walk away.
3. Inspect the body and screen in good lighting
Turn the phone at different angles under bright light. Look for dents, chips on the corners (a sign of drops), scratches on the glass, and signs of tampering (damaged screws, uneven gaps between the body and screen). Turn on a white background (open a blank page in your browser) and check the screen for dead pixels, spots, yellowing, and lines.
4. Test the touch screen and Force Touch
Open "Notes" or any drawing application and swipe your finger across the entire screen — the line should be continuous without "blind spots." Check all edges: sometimes after a screen replacement, the touch screen has dead zones around the perimeter.
5. Check battery health
On iPhone: "Settings" → "Battery" → "Battery Health & Charging." The capacity should be no lower than 85% — otherwise, the battery will soon need to be replaced. On Android, use codes (*#*#4636#*#* for some models) or the AccuBattery app: it will show the real capacity after a few charging cycles.
6. Test all cameras and flash
Take several photos and videos with the main, ultrawide, telephoto, and front cameras. Check autofocus, stabilization, flash, and the operation of all modes (portrait, night, slow motion). The images should be sharp, without spots or dark areas at the edges — this is a sign of a damaged sensor.
7. Check speakers, microphones, and earpiece
Play music — the sound should be loud, clear, and without distortion. Record a voice message and listen to it: if the voice is muffled, the microphone is clogged or damaged. Call someone and make sure the other person can be heard through the top earpiece.
8. Test all buttons and ports
Volume buttons, power button, silent mode switch, Touch ID/Face ID, fingerprint scanner — everything should respond on the first press. Connect the charger and headphones (if there's a jack): check that the device charges steadily and sound comes through both sides.
9. Check Wi-Fi, Bluetooth, GPS, and cellular connection
Connect to Wi-Fi, download a small file — the speed should match your plan. Pair the phone via Bluetooth with another device. Open "Maps" and make sure GPS quickly finds your location. Insert your SIM card — the phone should register on the network immediately.
10. Make sure Face ID / Touch ID work
On iPhones, a common problem is that Face ID or Touch ID stop working after non-original repairs. Ask the seller to register your face or fingerprint right in front of you. If the function is "unavailable," it's a serious drawback and a reason to bargain or refuse.
11. Check repair history and originality of parts
On iPhone XS and newer, in "Settings" → "General" → "About" (or "About This Device"), the system will show if the screen, battery, and camera have been replaced, and if the parts were original. The message "Unknown Part" means the device was repaired in an unofficial workshop — this affects both the price and the lifespan.
12. Request a receipt, box, and indirectly check water resistance
A receipt or box is not mandatory but increases trust in the seller. Ask directly if the phone has been submerged: even after drying in rice, the device eventually starts to "glitch." Look into the charging port with a flashlight — oxidation or green residue indicates moisture ingress.
What to do after checking
If all 12 points are passed, congratulations, you have a decent device. If 2–3 points raise doubts, bargain or look for another option. The most reliable way to avoid risks is to buy refurbished smartphones from trusted sellers with a warranty: each device undergoes diagnostics according to dozens of parameters, and in case of problems, it is replaced or money is refunded.
At APPTRADE, we only sell certified Apple iPhone, Google Pixel, and Samsung Galaxy smartphones with pre-sale diagnostics and warranty — you don't need to go through the checklist yourself; we've already done it for you. Check out our catalog and choose your next smartphone risk-free.