2005 MCS not starting after mod
 

I just finished putting my 2005 mini cooper s back together after changing the pulley and air intake. (Things didn't go smooth so I had to take off supercharger). After reconnecting the battery, and turning the key, the dash lights up, the stereo works, the fans and pumps kick on but it will not start. I did have the ECU out and the battery was disconnected for 12 days. Any ideas of what is wrong and what to do?