First boot your notebook to the bios by pressing the F2 key during the POST screen ( Asus logo )
When entering the bios you see directly the version number on your screen with some system info ( type cpu and mem installed etc )
Go to the Asus site and check the for the latest bios version of your unit. You cant find the latest bios in the download section. Unpack after downloading the file onto a USB stick ( root ).
Reboot your machine with the USB stick already in it with your new bios file and enter again the bios. Now go to the second tab "Advanced" and search for the option "Start easy flash" ( usual the 2nd option from above ). Press it.
Now in Easy flash you need to searh for your USB stick. Select your bios file. Your bios will check if its the correct file and ( just follow the on screen wizzard ) to flash your bios. After flashing reboot your system and yet again go to your bios with F2. Now set your bios to default factory setting by pressing F9 key and press after that F10 to save settings and exit ( reboot ). Done