Why I can't click any buttons in my widget?

Death function connected to “tick”

@G1K777: If your Death function fires on Tick, you’re creating a new widget every frame. Do Once does nothing there, when the function goes out of scope, the node resets.

Why do you fire it on Tick, wouldn’t it be more efficient and logical to fire it every time the player loses energy? Asking, as you may have other reasons, of course.