A.T.
I don't think is a good idea to lock his bedroom door, it really sounds cruel A.. I also have a son, he is now 3 years old, and I have a routine going on. I don't think is never to late to start it, but let me alert you is an ongoing battle/process. I give him a night bath, read a book, and put him in his toddler bed (since he is 3 now). He will get up maybe two times rigght after I put him to sleep. Both times, he just opens the door and goes to his sister's room. I tell him, it is time to sleep, look the moon is saying hello! and I point the moon to him. The 2nd time and have a firmer tone and mention that we are all tired and it is time to go sleep. I usually start my routine about 7:30 pm and I can say he is out about 8pm. It is not easy A., but you can't give up. The key is to be consistant. This is what works for us. Good Luck!