Well, it might be a surprise to you, but I actually tried to solve the first puzzle and I saw the writing on the wall roght away, maybe it is a game developer in me or something. Yes, many possible combinations, but none of them worked. It is not as easy as "0081" or "1800", the rest went over my head, because there is no indication of what exactly you want the player to detect. Is the code in the text, which corresponds to the letters on the digits? Tried that too, but nothing.
It is not about the challange, but rather thinking, why is the code that specific number/combination. And there are only 4 numbers, so you can't make up more than 4 digits. Nevertheless, there is no point in playing again, sorry. Wish you best luck with this.