Sometimes the madness is the answer. Maybe that's something that would help you. Working at it from a different perspective, that is. I don't like to outline much, it's never been conducive to my personality to do so. With the series I'm working on right now, I have the end scene clearly and firmly in mind, and I have a somewhat clear idea about how to get to that conclusion. Hardest thing for me is all the connective tissue. Sometimes, my writing ends up reading like a series of scenes rather than a progressing story. I feel you on that burnout. I'm on my fourth rewrite for what I'm working on and my ninth or tenth read-through. Lucky for me, each time I rewrite it, I have picked up some important new perspective that helps make it easier. Maybe if working from the end doesn't work for you, maybe you can work from the climax, then go in both directions at once. It's not chronological order, but it's different.