What country are you in? Here in the UK mobiles are covered by EU law and have a 2 year warranty. Over at the S4 forums we've had guys with no issues with warranty once KNOX has been tripped but I guess it varies on your service centres and such.
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Phone: OnePlus One 64GB
Rom: Saber Slim | Der Kernel: AK
Tablet: Nexus 7 2013 32GB
Rom: SkimKat | Der Kernel: Stock SlimKat
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