Iphone4 shows no service. Unplug the calling card and restart, but there is still no service. I can't make phone calls, send text messages or surf the Internet. What happened?

First, try to see if someone else's mini card on your mobile phone is still out of service. If it is still out of service, trust me. I have the same problem as you. Go to Xidan Joy City to repair the fifth floor of Apple. He told me that it was a licensed Hong Kong version, but I didn't have a Hong Kong bank card or a formal Hong Kong invoice for free maintenance. Otherwise, I will pay for it myself, that is, I will change the motherboard. The price paid for the repair is almost 1000 less than the original one. Alas ... but I still don't go to informal places to fix it.