Root BOG5 without losing data I dont care about tripping knox

I have my sons phone who passed away in an accident in October last year. I need the "kik" msgs off his phone hes on bog5 I cannot lose the data so downgrading is not an option is there any way to root this SOB without losing the data. I have been searching for this since December so Im just finally asking for help. I already talked to the Kik Vice President in Canada and have the way to get the kik data file off the phone but need root.

Please if anyone can help. Let me know