This link may help you (stress may)...
http://www.bba-reman.com/content.aspx?content=citroen_bsi_body_control_failure
The reset procedure looks like a joke to me - and I've never heard of a Body Control Unit before and have no idea what BSI stands for - life is just too complicated.
The "smoke" sounds somewhat terminal.
Good luck...
Peccavi
August 2009