@imrehg what? That's just strange. I own a hybrid (corolla), never had anything even approaching that happen, it 'just works'.
Though, if a hybrid hasn't been used for a LONG time, and I mean a looong time, then it can run down and it's a real problem. Entertainment system shouldn't be using the high voltage battery though...
So I actually suspect this is more that their 12V is screwed in that car (it's separate from the high voltage hybrid pack) and they as a rental company couldn't be bothered to replace it.
A busted 12V battery can be charged but conk out anyway as it can't hold the charge.