I think I mention this, as LS brought it up in her Cousin It interview.
She says that "people are saying" that she murdered Gannon on Sunday. Sunday night. I don't know who "these people" are but I think it was Albert's and Landen's family members. So she wants to give proof that he's still alive late Sunday night and actually calls Harley over to the camera where Harley is confused about which timeframe she's supposed to say she "saw Gannon."
So it makes me wonder, with LS so stridently insisting Gannon was still alive on Sunday night...was he still alive but severely injured? She tries to use the video, she uses the Burger King run and a presumed shared meal among Harley, Laina and Gannon (but not her) to show Gannon came back from GoG (neighbors were already posting about the possibility that she killed him there).
I looked into bludgeoning splatter patterns in non-fatal cases and found that quite a bit of blood can be generated with blows from a blunt object, but victim survived. There are some pretty gruesome cases where victim is left for dead, but crawls away and survives to tell what happened. Also, if the blood is primarily from scalp wounds, those stop bleeding relatively quickly. It makes me think of JonBenet and her inch skull fracture. That was a single major blow from something like a golf club or hammer, swung with great force while she lay on concrete (IMO). No blood on the exterior of her skull to speak of, she was dying from brain bleeding when she was strangled.
The cases with bludgeoning/blood spatter include the Kathleen Peterson case. Autopsy says it took her 90 minutes to bleed out from severe scalp lacerations (at the back of her head, so underlying vascular system was richer).
So I guess I'm leaning toward LS goes ballistic on Gannon on Sunday night about something (the candle story is probably made up). I don't know if that event caused some or all of the bleeding - but the cap on his head and his near inability to walk make me think that it did. Then she finishes him off on Monday afternoon, either with more bludgeoning (hard to do on a mattress though), a firearm (which if the bullet was still inside his head, there wouldn't be a ton of bleeding) or some other method as yet unknown.