Hi hon, I'm sorry no one has been able to help you yet
How does he do for day time sleep? Does he still take a nap? Tracy has a great plan for kids who keep getting out of bed, but I'm not sure if your LO is old enough to get it. I'll write it down and let you be the judge.
When you lay your LO down, let him know that you will stay in his room for 2 minutes and then you will go because it's time for bed. Stick with this time. Set a gentle timer if you can so that he knows you're keeping your word. When the timer goes off you say goodnight/sleep tight and then leave. You keep this up every night. In addition to this, you can make a little chart for him and every night he stays in his room he gets a gold star. When he's had a successful week, you go and do something fun he loves to do. Maybe there's a park he really loves but is out of the way for you, maybe the aquarium or an indoor play area. Something that isn't food or gift related.
Do you think that would work?