We can unplug the keyboard, SD card, USB and so on. Just turn on the power supply, and you can refer to these methods at this time. The first thing you can try is to press and hold the power button on the upper right 10 second. Then pause and press the power button to see if it is turned on. If it doesn't open, you can try again three times and repeat the above operation.
In addition, you can also operate by pressing the volume button and the power button. At this time, you need to press the plus sign of the volume button and press the power button at the same time. You also need to wait 10 second, and then observe whether the device is turned on.