What Sierrafery is trying to say (English isn't his first language, so bear with him, please) is that while the vehicle is immobilised no code reader will be able to communicate with it for security reasons.
You need to use either the keyfob or if that fails the EKA to switch off the immobiliser before anything can be programmed.
As he said, a dedicated code reader such as Nanocom, Hawkeye, Lynx or Testbook at the main dealer is necessary to program the BCU. It's extremely unlikely that a generic code reader will even gain access to the BCU.
Reprogramming the BCU can take some time because there are quite a number of settings which need to be checked and if necessary reset.
Sierrafery also gave you a link to a company who for a charge will repair your BCU maintaining your current settings and they will also tell you all the security information which has been set on it including your EKA.