K12 Key?

Hi,

I bought Nissan Micra 03 Plate K12 with out key from Salvage Auction with out Intelligent Key,
I tried to use second hand key with another Micra Same Age and has same intelligent Key System, so I changed the Key Cylinder, Key recognizer unit, BCM, ECU, and the door Locks, now every thing is working fine, apart from the car does not start!

I been told that the ECU needs resetting, some says Because it is used ECU it cannot be reset!

Any one can help?

Thanks