This resource has everything to get you started: https://www.hrv4training.com/quickstart-guide.html
I can't comment on how the Fenix defines unbalanced, but you generally want stable, but steadily increasing HRV as you work through your training plan.
I can't comment on how the Fenix defines unbalanced, but you generally want stable, but steadily increasing HRV as you work through your training plan.