I would guess that is has fermented, and it is probably quite good. I had a half gallon of fresh squeezed cider that got forgotten in the fridge. When I found it, the cider was nicely carbonated and had fermented quite a bit. I drank it and enjoyed it.
The experience made me think about what cider may have been like in colonial times. Make the cider and leave it outside in a barrel. The further into the winter, the harder it got