Life Happens... That's why we have fuses.
Same thing happened when we had or Cougar in for some minor warranty work. They had me come and pick up the trailer and the batteries were dead, way down on water and both 40a fuses blown.
Svc. Mgr. got the full version of my disgust with their operation. He brought out 2 new batteries and fuses. Offered to have his tech install but I said I'd rather do it since their QC and attention to detail was a "little suspect" in my estimation. Been driving 50 miles further for warranty work ever since.