Hi
Follow the steps here, including contacting Apple Support, making a Genius Bar reservation or visiting an Apple Authorised Service Provider if necessary:
After the phone has gone through the activation set up and it goes to the main page it loops itself back to the beginning of the activation set up. The phones just fine without the SIM card. I’ve tried multiple SIM card with various carriers and none of them work. The phone was bought at Best Buy paid full price with no carrier. With iPhone 7 being a universal there shouldn’t be any problem with any sim being used.
Best Buy does not sell unlocked phones. Never. Period. They lie and say they are unlocked, but they will lock to the first carrier they are used with, and must be a US primary carrier (not an MVNO). Depending on which model you got, they may not even work with Verizon or Sprint - just AT&T or T-Mobile (US).
Please explain what you mean by an "activation loop"
iphone goes through an activation loop
