I have a question: If, for example Burke, would have used the flashlight to strike JBR (not intentionally as hard), would the flashlight have had visible blood on it?
I am just going by the theory that Burke didn't mention the flashlight was the main weapon... maybe one of the parents used it to dispose of evidence (it was dark outside) and then wiped in inside and outside just to make sure, hence why it was left on the counter - it had no value to their story or to them.
It would just fit the story well that Burke did take the flashlight downstairs as he said himself that he went down to play with toys after everyone else was asleep, of course he wouldn't want to turn on all the lights in the house. I am a few years younger than Burke but I remember also using a flashlight at many times at night, especially before Christmas to peek into the presents