M iPhone show unable to activate

Try to take out the SIM card and activate it. If there is no SIM card in the phone, put a SIM card from the carrier you bought the phone from. Ex: Verizon, AT&T, etc. Sometimes if you take the SIM card out and blow in the SIM card tray at an angle, it may get some dirt out on the pins, although I don’t recommend it unless you have no other choice. Then, put the SIM card back in. If none of those options work, try to plug it into iTunes and update/restore it from there, and then see if you can get into it.