Bexx

Bin file found first time plugged in, encoded, what is its execution? And if its rewritten, what happens to it

A friend if mine told me they opened theirs out of the packaging and first time plugging it in their was an encoded bin file already on the SD, so they overwritten it with their own? Before they overwrote it though, is my question? Could the bin file be anything? Or was it needed, embedded and needed, etc?