Last year I bought my iPhone 6S plus from a local store. It was a brand new device and i checked this in Apple Support Website.
previously I updated my phone using DFU mode to newer iOS versions (from 10 up to 11).
last week after install iOS 11 my phone lucked down !!!
after checking AT&T website, it said that my phone is locked because its stolen !!!!
i'm sure that my device was brand new and it was indeed.
please help me with this problem.