I can understand that one might burn out on the whole zombie thing, or really, anything, if you're spending most of your time plotting, planning, and working on it every day! I'm working on my first novels, but they're going so slow, so well done on getting your first novel completed and published! I do hope that perhaps you wont give up on your series just yet, take a break and then go back to it? Best Wishes!
Haven't given up, just taking longer than I anticipated. Thanks for reading!