my c3 will not start according to lexia 3 the bsi unit is faulty the bsi is matched with the engine ecu , the engine ecu is locked and key 1 through to key 5 has come up as not sychronised when the engine ecu is locked lexia says the bsi unit and engine ecu have not recognised each other i have checked all fuses and wiring everything is ok will this mean buying another bsi unit ?