My mobile phone can send and receive short messages, but it can't surf the Internet. Always flashing back, there is no sim card in the upper left corner. After the call, it flashed back to the main bo

My mobile phone can send and receive short messages, but it can't surf the Internet. Always flashing back, there is no sim card in the upper left corner. After the call, it flashed back to the main border. ... Android system? Contrast test, change the mobile phone card to someone else's normal mobile phone, and the normal test proves that the mobile phone card is no problem. Putting someone else's normal mobile phone card on your mobile phone is still the same problem, which means there is something wrong with your mobile phone system or hardware. After it is proved that it is a mobile phone problem, we can start with the system first. If you use a smart phone, it is a hardware problem and you can only go to after-sales maintenance. I hope I can help you.