How to test a used iPhone before you buy or sell it?

Some of us can’t or won’t spend a lot of money on a new smart phone. In case of the iPhone, market of used phones is alive and kicking, so we can get a good used one for a decent price. Off course, that does not mean we should buy whatever seems nice to the naked eye. We should always test before purchase.

Here is a short list of things that can be done to test an iPhone before purchase:

1. Determine which model it is and how much storage it has by going to:
   • Settings
   • General
   • About
   • Storage size is stated in GB which is self-explanatory, and you can find out which model it is by googling the model or serial number
2. Remove the screen protector, skin and case, if any
3. If the phone is not clean, clean it to be able to check for scratches and other physical damage. For that you’ll need:
   • Gadget-safe cleaner liquid
   • Soft microfiber cloth
   • Good source of light
4. Check your phone for water damage (for phones not water-resistant, 6s and 6s Plus and below). You can do that by angling the headphone or power jack towards you and positioning the light source to reveal the liquid contact indicator in the bottom of the jack. White indicates no water damage, pink or red indicates exposure to excess moisture.  The 3G, 3Gs, 4, and 4s have an additional indicator in the charge port that should also be checked. If you can’t see the indicator, clean the connector carefully to be able to check. The iPhone 5 and newer will have an indicator located inside the SIM card slot
5. If if the phone is not already returned to factory settings, do that before proceeding. You can do that by going to:
   • Settings
   • General
   • Reset
   • Erase all Content and Settings
6. Put your SIM card in
7. Do the basic setup, and login to your accounts by using your Apple ID
8. Check does the IMEI numbers on the back of the phone or in the SIM tray and in Settings Match
   • Settings
   • General
   • About
9. Next you should do the basic functions test to see if the most important hardware and features are in good and working conditions:
   • Press the power button to check if it works properly
   • Connect the phone to a charger to see if it will charge
   • Connect the phone to your laptop to see if it will connect to iTunes
   • Do a call test with a friend to check the phone, speaker and microphone
   • Test the volume buttons by pressing on them and see if they work properly
   • Use the mute toggle to see if it works properly
   • Test the touchscreen by moving na icon across the screen
   • Test the accelerometer by opening any app that has both vertical and horizontal interface (such as Calculator), and rotate the phone in your hand to see how it behaves (check if the rotation is enabled before)
   • Test the camera by opening the app, taking photos and recording videos. Examine the photos and videos taken by visually inspecting them
   • Test the Wi-Fi by connecting to an AP and doing a browse and a speed test
   • Test the Bluetooth by connecting headphones and listening to some music
   • Test the GPS by using Maps
   • Test Lightning or 3,5 mm Headphone connector for sound output by connecting headphones and listening to some music
   • Test the speakers by:
     • Listening to some music on them
     • Doing a call on speakerphone
   • Test backlight by going to Settings, choosing Brightness and moving the slider and observing how the screen behaves
   • Test home button by using it
   • Test fingerprint sensor by enrolling your finger and trying it out
   • Check the display for dead pixels and contrast levels with Screen Test app
10. Benchmarks are always a good test. Some benchmark you can use for free are:
    • Antutu Benchmark
    • 3dmark Slingshot
    • 3dmark Ice Storm
    • GFXBench GL
    • R Benchmark
    • Basemark OSII
    • RAM Benchmark
    • Linpack
    • GFXBench Metal
    • https://browserbench.org/JetStream
11. If you have time, do the battery durability test (check how battery drains over time (in standby and in use)), if not, check the health by going to:
    • Settings
    • Battery
    • Battery health
    • Anything above 80% is OK
    • Below 80% can be changed for arround USD/EUR 25 depending on where you are in the world

All this test results plus what comes in the box determine if the price is worth it or not.