I know a little about cars and I've replaced the battery and alternator, but my car still has trouble starting. I'm thinking it could be the electronic control unit. Do you agree and if so, how do I get to it in order to repair/replace it?
Before you go replacing any additional components I would suggest calling a mechanic, like one from YourMechanic, to come to you and diagnosis the no start problem for you. It will save you from guessing on what is the problem.
If you have a no crank condition then a starter relay or starter may be the problem. If you are having a crank no start then you may have a sensor failure or antitheft system problems. Call the mechanic to diagnose the problem.