A nice and challenging escape game! It took me trials and errors to figure out how to get a fingerprint to switch on a computer with a broken screen. Hint: print an image of it. Other than that, I had no problem finding the three codes which are required for unlocking the security chains.
The clue note about hexadecimal calculation is self-explanatory. You just have to replace the symbols in the example with three other numbers converted from letters. c: