Cracking

I have managed to find the serial number that produces the "The serial number is correct. GG you’ve p0wned Me :D". I run the unmodified binary on my Ubuntu system. MD5sum: 3e83496ed6014d8cdd7694d8f4eb08d3

With the username: Root-Me
Serial number not posted for obvious reasons.

But when i try to submit the serial number that gets me the correct message on the site, it gives me an error. Any advice?

Sorry for the spam... Turns out I had to log out and log back in. Sorry for the confusion. Challenge solved and points have been collected. Thanks