Check if the iPhone is locked
If you bought your iPhone from a reputable website, you should not have to deal with this type of problem. However, if you are going to buy a used iPhone from a private individual, it is best to check that it has not been locked by its owner.
To find out, simply turn on the device. If you see a screen that says the iPhone has been locked by its owner, it means that Activation Lock has been enabled. If so, run away. Similarly, if the iPhone appears to have been reset, start setting up the device until iOS prompts you to connect your iCloud account. If the device has been locked by its rightful owner, you will not be able to set up your iCloud account. Run away, because this means that the device has probably been stolen.
Alternatively, if the iPhone has not been reset by its owner (if you have to type in the screen unlock code and you immediately arrive at the device’s home page with applications), ask its owner to reset the device in front of you. To do this, he will have to go to Settings > General > Transfer or reset iPhone >
Erase all content and settings . By doing this, he will be forced to enter his iCloud account password, and by extension to deactivate the Find My function, which allows you to block an iPhone remotely.
Check the serial number on the Apple website
This will let you know if it is still under Apple warranty, but more importantly, you will get its purchase date. This will let you know if the device has been mistreated or not, based on its physical condition.
Check if the device has been repaired before (and if it includes non-official parts)
For several years now, Apple has been in the habit of integrating software protection measures into its iPhones to prevent users from repairing them without going through an official channel. A digital lock called serialization and which associates the serial number of a spare part with the logic board of the iPhone. Apple does not like it when people try to repair an iPhone outside of its authorized repairers,
While the screen and battery are likely to have been replaced without any major issues in using the device, other elements may prove more problematic. This is the case, for example, with the front camera module, or even the entire speaker and proximity sensor (which are grouped on the same part). In the event of a change of these elements, even with an original part, the Face ID biometric identification module will no longer work. In this specific case, professional sellers generally indicate this in the product description.
Check the battery condition
The health of the iPhone battery is also an excellent indicator of the wear and tear of the device. On its website, Apple indicates that the batteries of its devices are designed to operate optimally, that is to say to retain at least 80% of their original capacity, for approximately 500 charge cycles . Apple has also implemented for several years now a tool in iOS allowing you to know if your battery is in good condition.
You can find this information by going to Settings and then, in the Battery menu , go to the Battery health and charging section . You will then see the maximum capacity of your device’s battery. Above 80%, the battery is considered to still be in good working order. Below that, it is advisable to contact Apple’s after-sales service to have it replaced. It will cost you a good hundred euros. You can get an estimate of the cost of the repair by going to this page .
Check the touch screen status
Even if your iPhone screen seems to be in good condition, it is best to carry out a few checks to avoid unpleasant surprises. Beyond possible dead pixels (which can remain bearable), it is essential to check whether the screen’s touchscreen is functional over its entire surface. To find out, switch the home screen to edit mode by holding your finger on an application icon. Then select any icon and move it slowly in a grid pattern on the iPhone screen. If the device’s touchscreen is faulty, you should see it very quickly since when you move over the affected area(s), the icon held under your finger should no longer hold.