UK Car Repair Questions? Ask a Mechanic for Answers ASAP
I am sorry that you have not been helped yet. I just came online and saw your question
Ok, first, what is the year of your 300c
Second, is the security light staying on continously or flashing on and off?
third, if antitheft is working properly, you need fuel, spark, and compression for the engine to start and run. I see what you have replaced, but have you tested each to see what is missing - fuel, spark and compression