Then root it run triangle away, unroot then send it in for warranty?
Exactly. But when rooting use chain fires tool. It'll keep the stock recovery.
And you might have to factory reset to get official status back, I had to when I did it.
Thanks worried a bit after flashing TWRP.
Cydia impactor also leaves stock recovery
personally I don't like stock recovery because you can't quite backup your phone in case something goes totally wrong. I prefer custom recovery and when I need to send for service I simply flash stock using Odin and go.
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