Boot into download mode to confirm the model #. You should not attempt to flash anything until you confirm the model #.
The Canadian s3 is the sgh-i747m. AT&T s3 is sgh-i337 (no m at the end).
so which rom of cm or lineage should I install in my canadian Fido SGH-i747M? (I prefer any marshmallow version, otherwise android version 5.x ). thanks