On a Fusion control, you'll have a MR-J2 drive that probably runs that. The battery is not much different than a FANUC drive battery. On that machine, I'm not sure where the drive is located. I'd check the power cabinet. But on many other machines, a drive(s) is also located elsewhere. For example in the tool change area under a panel or something. Look in you parts book for all of the MR-J2 drives. On the front of the drive, you'll see a couple flip up covers near the top. Behind that is the battery...
It's just a part..... cutter still goes round and round....