1. For the first time using, plug in the battery
2. Check whether the battery has been charged for 2 hours and then replace the adapter to charge it
3. Replace other batteries
4. The startup operation is to press the on/off button until "android" appears on the screen and then release it.
5. Check whether the power button is depressed or damaged
6. Check whether the startup has a backlight. It has a backlight, the LCD is not plugged in properly or is faulty. It needs to be replaced