Hello, good day. Please help me out. I bought a CHUWI Hi9 Plus tablet some months ago. I have been using the tablet, until one day when the screen(display) suddenly went blank but lighted up. Since then, the screen has remained blank and lighted up and I can’t use it again.
Please I want you to reveal to me the exact button 
step by step sequence of how to HARD RESET (format/restore to factory state) my tablet, using the POWER & VOLUME KEYS, considering the fact that the screen is completely blank(no display) and possibly forward a VIDEO that demonstrates how to carry out HARD RESET of a CHUWI Hi9 Plus tablet.
And please recommend for me an ANDROID DATA ERASER (Computer Software), with which I can format/erase all data from my CHUWI Hi9 Plus tablet.
Thanks.