White blocks on LCD screen after Anet A8 power up
This is a known and documented problem of this printer. I'm afraid your printer board is dead.

If you have white squares on the display like this picture:



  You need to check Anet A8's mainboard - click reset button and check
  the D1 indicator:
  
  
  
  If D1 lights on for a second then went out and the screen is full of white square, try to reconnect screen wire for several times. When
  it's well connected, click the reset button. If still not working, you
  need to replace a screen.
  If the D1 indicator is always off and the screen is full of white square, you need to replace a mainboard.
  


From the video you posted it can be seen that the D1 LED does not light up, it is off the whole time. Hence the main board is dead.