How To Check If A Used Phone Works Perfectly: A Simple Guide

Buying a used phone can save you money, but you need to make sure everything works properly. Don't worry-you don't need to be a tech expert! Follow these easy steps to test a used phone like a pro.

 

1. Check the Phone's Physical Condition

Look for damage:

Shine a bright light (like your phone's flashlight) on the body. Check for scratches, dents, or cracked edges.

Open the SIM card tray. If it's dirty or rusty, the phone might have been repaired poorly and could have water damage.

Test buttons and ports:

Press the power and volume buttons repeatedly. They should click smoothly.

Plug in a charger to check if the port feels loose or doesn't charge properly.

 

2. Test All Hardware Features

Screen and touch:

Open a drawing app and scribble all over the screen. If lines skip or stop, the touchscreen is faulty.

Display solid-colored images (red, white, blue) to check for spots, discoloration, or uneven lighting.

Cameras and sensors:

Take photos with front and back cameras:

Point at a white paper to test focus.

Film a moving object to check image stabilization.

Look for dark spots in photos (could mean dust inside the lens).

Test sensors:

Cover the top of the screen during a call-the screen should turn off.

Rotate the phone while using a map app to see if the direction changes.

Speakers and microphones:

Play music and cover the speaker holes. The sound should get quieter.

Record a voice memo and play it back. Test both the call mic and video mic (some phones have separate ones).

Wi-Fi, Bluetooth, and SIM:

Connect to Wi-Fi and download a small file to test speed.

Pair Bluetooth headphones and play music.

Insert a SIM card and check signal strength (compare it with another phone).

 

3. Check Software and Performance

Reset the phone:

Ask the seller to reset the phone in front of you. This removes hidden accounts or malware.

Test for hidden issues:

Record a 4K video for 20 minutes or play a heavy game. If the phone overheats, crashes, or restarts, there's a problem.

Verify hardware info:

For Android: Use a free app like CPU-Z to check if the processor and RAM match the official specs.

For iPhone: Go to Settings > General > About to check the model number (e.g., CH/A means it's a China version).

 

4. Look for Hidden Repairs or Fake Parts

Signs of repairs:

Check screws on the bottom. If they're scratched, the phone might have been opened.

Gently run your fingernail along the screen edges. If it feels rough or has glue residue, the screen was replaced.

Battery and storage:

iPhone: Go to Settings > Battery > Battery Health. Below 80% means the battery needs replacement.

Android: Dial ##6485## (works on some brands) to see battery health.

Test storage speed with apps like AndroBench (Android) or Blackmagic Disk Speed Test (iPhone). Slow speeds could mean fake storage.

 

5. Avoid Scams

Check official records:

For iPhones: Look up the serial number on Apple's website to confirm warranty status and check if it's stolen.

For Android: Visit the brand's website and enter the IMEI number (dial *#06# to get it) to see repair history.

Too good to be true?

If the price is 30% lower than average, it might be a fake, refurbished, or locked phone.

 

Quick Final Tests (Don't Skip!)

Water resistance test: Gently blow into the microphone hole. If you hear air leaking, the phone might have water damage.

Motion sensor test: Open a compass app and rotate the phone. The needle should move smoothly.

Fingerprint/face ID: Try unlocking the phone 5 times. It should work fast and consistently.

Stress test: Open multiple apps (camera, game, video call) at once. If it freezes or crashes, avoid it.

 

Pro Tips:

Buy from platforms with return policies (like eBay Refurbished or Amazon Renewed).

Film your tests and save chat history with the seller in case you need to return the phone.

 

By following these steps, you'll avoid most problems. If you're short on time, at least test the cameras, play a video, and make a call. Happy shopping!