Master disconnect on fourwinds 5000

She was driving a when she arrived at her friends home she attempted to start the generator and found the battery was dead and the master switch just had a FIM glow and would not turn off. So she had no lights, water pump etc.....no shore power where she ended up having yo park the coach. The battery was brand new top of the line 300 dollar battery....something drained the battery while she was driving. It was only a 10 hour drive and it's completely dead...just can understand why it didn't charge as she drove or what could have drained a brand new battery that quickly. She is a nervous wreak as am I..thankfully the engine starts and runs fine m it's just the house battery that has the issue, sorry if I wasn't clear...scrambling yo get an answer yo help her...she not very good under pressure...