A factory reset really doesn't remove all, especially if you have chosen to try and save your personal stuff during the reset. I would suggest trying again (after backing up your personal stuff to another device), but this time do a "Hard Reset". If that then doesn't fix the problem, it may be hardware and not software that is the issue.
NOTE: Doing this will clear 'all' the data on your phone, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the phone.
Be sure you back up any data you want to keep, to a computer or cloud account, before doing the reset.
To "Hard Reset" the phone...
1. Make sure that the phone is actually powered off.
2. Remove your SD card, if there is...