that is not an explanation, he simply told you what happened, the cause and the effect isn't the same thing dude you just associated correlation with causation on your own.
you clearly didn't even look at what i linked,
of course you can get damage in organs at 39, as in 38, 37, 36 35 and so on, but the cause of damage won't be the temperature, unless you have (as i mentioned before) a severe comorbidity/comorbidities, that make/makes the fever dangerous in your particular case
what is your source on 40C being deadly? however if you want to tell me another anecdote or link me a case of sepsis patient/4 months old infant, then you can get lost