My 3 year old grandson recently passed away in france where he lived, autopsy report stated gastroentritis as the cause of death, with bleeding. ?

Hard to comment: A bad gastroenteritis could certainly lead to dehydration & death if not quickly controlled. You can also have a bloody gastroenteritis with some forms of e.Coli that can cause the kidneys to fail, hypertension & coma. I'm sorry for your loss.

Get an autopsy: I would not accept "gastroenteritis" as the cause of death of a previously-healthy three-year-old in a developed nation such as France unless the parents were extremely negligent in his care. An intussusception or other intra-abdominal catastrophy, or a vicious colonic infection by an aggressive bacterium, or many other things might be the cause. I'm sorry for your loss.