[Q] firmware topic

Hi, I got a videotron (canadian carrier) note 4. Unlock and using it on rogers network. I bought it second hand, and seller didn't told me about the root..... On sammobile site, for the firmware, all canadian carrier have model sm-n910w8 as model #. Is it safe to flash rogers firmware on it? And is there a way to see if knox (probably been tick off) how many time and anyway to reset it. Looking through google but a bit lost. Thanks for your help