Landing jack problem

[psomers]

This is for a friend that isn't very familiar with RV repairing. He has a Montana I think 2018. He is in Gulf Shores so too far for me to look at the problem. Before leaving home he had a door side landing jack leaking. He decided to wait until arriving at Gulf Shores to fix. Had it repaired and reinstalled. Camper was hooked to truck during all this jack repair. Now when trying to lift camper to unhook from truck he gets flashing inside 12V lights and low voltage displayed. He is trying to remove cover from batteries and can't get the cover off. He sent me a picture of battery box and I've never seen one that has the terminals be part of the cover. I'm sure he has two batteries as he has a residential refrigerator. Any help?