in a first moment, the carrier signal was ok, but data wasn't working. so i called the carrier, get the correct APN, and the everything was fine for 5 minutes, for phone calls, data network. But suddenly signal was lost, and never got back. Factory reset, the signal bars still off, with an X. Tried to locate the carrier manually, but it doenst work. What can I do now? I will try another sim card to check if it works. How do i know the phone is carrier locked?