I have borrowed my friend's old kindle to read some files on it. They were plenty and he had a large archive himself. So, I had to transfer them somewhere else. But the capacity was still full so I formatted it (To exFat)🤦🏻♀️. Now I have all the files on its folder but it doesn't recognize them on the device. I'm panicking. What shall I do? I don't even know the model. Its quite old, non-touch, doesn't have background light, a square and four other bottoms on it.