How do I remove Trojan horse virus from my android smartphone?
It seems that the virus has violated the boot area of ​​the smartphone. It seems that treatment is difficult in factory initialization. Therefore, you need to directly download the new genuine official firmware and reinstall the firmware.

All data is deleted, you can install genuine firmware and return all things to the initial state.

Even though one can do it without difficulty, in case it is difficult get the help of the official repair center.