This situation is generally not to find reasons. I don't know what the reason is without testing, just try it in the following way. For example, a mobile phone with mechanical and electrical separation can be started by removing the battery from safety to see if it is useful. Restore, restore, and see if this phenomenon still exists.

1. Double clear data can solve this kind of problem; Press and hold the power button and reduce the volume (some press it to increase it), then enter the recovery mode.

Some mobile phones are an exception. Press and hold the volume up key, volume down key and power on key at the same time, and release the power off key after the mobile phone vibrates (the volume up key and volume down key remain pressed) before entering. Different types of mobile phones have different access methods. After entering the recovery mode, there is a robot lying on the ground with an open stomach. At this time, press the main menu or house key to see the operation interface. Pay attention to the following two lines after entering: Erase data/factory reset Erase cache partition. Some mobile phones choose the volume up and down, and the power button is confirmed. Move the cursor to Erase Data/Factory Reset, and then confirm the input. When you see a lot of no's, one line is yes. Move the cursor to the Yes line and confirm. In this way, the first step of double clearing is completed. A few minutes later, a little longer. You will return to the recovery home screen. Then enter the Erase Cache partition to clear the cache, then select Yes to confirm, and the second step is completed (if your mobile phone doesn't respond, please Baidu your mobile phone model+Double Clear).

2. Restoring the appearance setting can solve this kind of problem;

3. Brush machine should completely solve the problem; (Simple card brush, also wired brush detailed tutorial please Baidu)

If all the above methods fail, you can go to today's after-sales maintenance.