Ok then. from your blueprint just replace the Enable and Disable Input with a new bool variable. On your input events, branch to check that bool, and then if true, activate or deactivate it.
Also, select the Z and X key events and in the Details tab, make sure Consume Input is checked. I think it might work that way.
Edit: this is just to turn the light on. But the radius to turn on the fire isn’t the same as the radius to burn the player is it? So, I think you have to add another trigger, a smaller one, to start and stop the timeline
Hope I’ve been clearer