You have a phone with a real, but subtle fault. Something not caught by the normal set of tests. You return it for repair, get sent a new one, they replace the battery in your old one and put into stock as 'reconditioned'.
My phone is perfect, save for a worn out battery. I send it in for battery replacement, they send me yours. Now I've swapped my perfect phone for your faulty phone - and paid $70 to do so.
You have a phone with a real, but subtle fault. Something not caught by the normal set of tests. You return it for repair, get sent a new one, they replace the battery in your old one and put into stock as 'reconditioned'.
My phone is perfect, save for a worn out battery. I send it in for battery replacement, they send me yours. Now I've swapped my perfect phone for your faulty phone - and paid $70 to do so.