Core installs the main tool software for your robot - handling, arc, paint etc. through the BIOS. Depending on the version of core provided there are different personalities - software options like vision, dcs, etc. as well as robot model like 200iD S, 200iD SH, etc. An Image backup is strictly a copy of an existing robot.
I'm assuming at Fanuc they had handling tool core with multiple personalities - 1. R2000iC/125L 2. R-2000iB 210F 3. etc. and they loaded in the wrong personality by mistake.
So if I took Image Backup from the existing robot which is the same as a new one, and load to the cabinet everything should be ok.