Simply make sure :
1) Vibrate switch is working
2) Volume button is working
3) Sleep wake is button working
4) Home button is working
Go to settings > General > About > IMEI
note down this number and paste it at ( iphoneox.com ) and see if it's in black list or not.(in case if it's stolen! )
6) Mic working (record your voice, open utilities and find the
recorder)
7) Speaker working (play what you recorded)
8) Proximity sensor working (cover the sensor while playing the
audio clip)
9) Wi-Fi working (turn on and off and make sure networks show
up)
10) Blue tooth working ( same process as wifi)
11) Camera working ( take some pics)
12) CPU is working good
Record a 10 minutes video, if the CPU has
any problem, the phone will shut down and restart during the 10 minutes
recording.
13) Make sure you can call!
Insert your micro SIM card and make some
calls. See if there’s any audio lagging or any problems of that sort
14) Turn off the find my iphone option
Go to Settings > General > iCloud > Find my iphone and turn it off
Ask the previous owner’s
icloud password (if he/she has created any) because if you reset the iphone and you don’t know the icloud
password, you’ll be stuck, this is very important guys.
If the previous owner hasn't done much about iCloud then there is nothing to worry. You can create an iCloud account and set it for your device.
15) Headphone jack is working
Plug the ear pod and listen to something
16) USB jack is working
Carry your laptop and check the USB jack is OK.
If you can’t find any
problems yet and If you’re satisfied with the scathes and all (If it has
any), you're good to go! BUY...
Leave your comments if you have to know anything more.
