1. Check whether the seal of the packaging box is complete, if it is not complete, it may be post-sealed.
2. Check the appearance of the packaging box to see if there are signs of wear or fingerprints. If there are such signs, it may be used.
3. Check the appearance of the phone for signs of wear or fingerprints. If there are such signs, it may be that the phone has been used.
4. Log in to the mobile phone system and check the system activation time. If the system activation time is too early, the mobile phone may be backlocked.
Hope the above information is helpful to you.