Hello I've got my iPhone 5S' replaced multiple times, and they always tell me not to put in you Nano SIM card at the Apple Store, wait 20 min after it's on, then put in your SIM card. Has anyone ever heard of this? I wonder if it works on locked phone replacements. I guess when you get a replacement for a locked phone they put in the SIM card and turn it on for you, without telling you this. What a strange set up!