what happens if you turn the phone off then plug it into a power source
ok so if you had a custom recovery installed then u can factory reset it by pressing vol up and power till u get to the menu. then factory reset, reboot then when u boot it will boot to your custom recovery and you will have to restore a backup .
if u dont have a custom recovery then u should also factory reset then reboot then install the official update.zip but make sur u have all the files before beginning.
now factory resetting will mess up your phone so try everything first before doing this.
I also saw in your video that u werent pressing the buttons long enough you MUST hold them till u get a menu.