Step Flash ROM:
1) Wipe cache, dalvik-cache, data, metadata
2) Flash ROM
3) Reflash custom recovery
4) Format data (required for encrypted devices)
5) Reboot recovery
6) Flash custom kernel (optional)
7) Flash DFE (optional, for decryption)
8) Flash magisk (optional, for root)
9) Format data
10) Reboot system