If you have 12 V on one stud and 0 V on the other, that device or its connection is open or has high resistance, but the description alone isn't enough to call it a fuse or size a replacement. With the battery isolated, check continuity through it and inspect the terminals; if its rating or...
One thing worth separating is the charging/operating limit from the storage limit. A power station left in a parked cabin can get hotter than its published rating even when nothing is running, and the pack electronics may have different limits from the cells. I'd use the exact...