It is "chain" of events, not "train" of events.
1. "Forgot locking the door" probably doesn't work. "Forget" is one of those verbs that create a different meaning when they take a gerund instead of an infinitive. "Forgot locking the door" means the person locked the door but forget doing it. "Forgot to lock the door" means the door was left open. The latter is more likely to fit the context in your sentence.
3. I don't think "not interested in" is strong enough to match the end of the sentence.
Student or Learner