Why does the mobile phone always show some mushrooms with panda heads?

Enter the line brush mode due to misoperation.

It is usually the quick start mode of Android phones. Fastboot is a lower-level brushing mode than recovery in Android phones. Simply put, it is the brush mode of connecting the computer with USB data cable.

Is to use recovery to empty the system and insert the cache directly into the computer and inject it into the system. Personally, I think this method is faster and simpler.