Traduciendo paso 8
After third washer has been installed and the screws have been tightened touch the power pad on the motherboard.
If the PS4 makes no noise and shows no lights then the screws are too tight...loosen screws very slightly (about 1/8 turn) and try to power it on again. Do this until the console powers on.
If the console still turns on and back off after these steps have been done then this fix will not work for your PS4.