How to make a character going back on his waypoint when overlapping ?

Hello !
I just started UE4 some days ago for my studies, and I have some issues. I have a monster wandering in the corridors along a path I created. I used a Behavior Tree and a BlackBoard for that. But I would like to, when the player have his light on (a simple light that I grouped to the player and that can be turned on and off with F) and when the monster enter a sphere collision around that light (else than the basic capsule of the player, and that is bigger than the kill zone around the monster), the monster go backward on his path, or is stun for some seconds. But when the light is off, the monster doesn’t care about the sphere collision and kill the player.
You can see my Behavior Tree below, I followed a tutorial for the increment, loop, and decrement for the path. But the decrement here happen at the end of the path. I tried (I say, I tried, without tutorials x) ) to create a new task that I called OverlappingLight, so that check whether or not the monster is overlapping with the light, but I might say that I don’t really know if it’s the best idea or not, and I’m sure it’s not, or I did something wromng in it, as it doesn’t work x)
Any ideas how I could do that ? If it’s understandable, what I want, of course x)

Thanks in advance !