peugeot 406 hdi imobaliser problem?

1999 406 hdi had petrol put in/ drained right off/ bled through/ plenty of diesel up to injectors but seams to be cut off at that point/ no firing or smoke out of exaust at all. prasum imobaliser problem. the car will fire on arostart into the air intake bypassing injectors. the car has stood for awhile and battery has also been compleatly flat. any body got a way round this problem