peugeot 306 wont start?

earleir this year had a problem with 306 dturbo that had just bought some body backed into it. repaired the front and that and now the battery has gone flat has got everything right with it when ive charged the battery a lil of a jump it just wont start it has an immobiliser that has green and red light on second turn of key but just ticks doesnt turn over, what is the problem??is it the imobiliser or something else oh the radio is asking for a code to.