Root King Root fail Note 4 At&t on Cricket

[solrak]

Hi i need help, i have a note 4, on At&t unlock running on cricket wireless, i try to root it with king root, it work, but only as temporary, now my phone does not work right it lags for everything, videos, wont play, key board is slow, and lock screen is low to respond, i factory reset and its the same, and delete, and still wont work, i try to emergency reset, with kies 3 and it ask for recovery code or password, and noting comes out on kies, this phone was bout, on eBay, my first post sorry for my spelling, any help appreciated, thanks