There may be many reasons my friend, you can look at this.
1. the press button is broken
The power button is broken, no touch, leading to the power button can't normal be used, need to assemble the machine shell key or FPC ribbon cable again.
2. the battery is bad
Plug in the adapter after the charge indicator has a flash, boot prompts 100% power, the adapter pulled out it immediately shutdown, this phenomenon is a bad battery problem, you can replace the battery;
3. the display is bad
Turn on the tablet, the back of tablet appear light display, forced long press the power button for 15 seconds can also appear a normal backlight prompts to turn off, the tablet this phenomenon is in consequence of bad display, you can replace the display;
4. the display FPC cable is bad
The customer accidentally thrown the tablet in the cause of using it, or the battery loose lead to the display FPC cable fall off, resulting in the machine does not boot, need to disassemble the flat battery power and re-insert the FPC cable, or bad cable need to replace the cable.
5. BIOS drop out
Need to disassemble the machine with a jig on the computer to brush BIOS, it can not directly use U disk to operate;
6. bad motherboard
The motherboard is bad, and the hardware needs to repair
You can try this my friend, I hope it can be helpful.
Have a good day!