Hi. This is normally a malware that infect core/main android system files. Have you tried a hard reset with no results? If yes, then this is because the malware becomes part of your system files. Making a data wipe to have no effect to it. A firmware/software reload is normally a sure remedy. For us to be able to assist with the firmware, we will need you to open the back cover an note down the system board ID and share it with us.