First off, rooting your phone DOESN'T void your warranty, it may seem like this because it trips knox or the binary counter. When you root and install superuser, it will remove the knox counter making that safe, and you can install Triangle Away by Chainfire to remove the binary counter. I have returned a rooted phone, and they checked only for the counters, which seems that's all they do at verizon, so I was fine even w/ my phone rooted.