I didn't read the text message, and the small light above the mobile phone was on. Why is the mobile phone locked after the screen is turned on (without reading short messages), and the small light so

I didn't read the text message, and the small light above the mobile phone was on. Why is the mobile phone locked after the screen is turned on (without reading short messages), and the small light sometimes lights up and sometimes doesn't? Remind me if there are any messages I have read. After reading the information, try to turn on the small light on the lock screen. If it is still open, please close it and restart it. If it really doesn't work, back up data and applications and restore factory settings. I hope I can help you (my mobile phone happened once. After reading it, remind me if there is any news I haven't read, clear the memory and mark all the things I haven't read. Finally, everything is fine. What methods have been exhausted? number