2005 Mini Convertible won't turn over.
 

I have 2005 Mini Cooper Non S. I have recently run into a problem where my my Mini will not start, the starter is working fine it seems and it is cranking but it isn't firing at all. I checked all the fuses and changed one of the larger green ones and also changed my fuel filter and cranked it for well over 15 seconds to try and get the engine started but neither of those seemed to work. There are no error codes borrowed a code reader from my dad and nothing came up. I am trying to fix it myself just to save some cash while I am still in college but I'm not sure what should be my next step