I think your best bet is a clean install. From another PC use Windows Media Creation tool
https://www.microsoft.com/en-us/software-download/windows10 and create a USB stick to install from. Afterwords download Nvidia drivers
http://us.download.nvidia.com/Windows/382.05/382.05-notebook-win10-64bit-international-whql.exe and from ASUS support
https://www.asus.com/us/Laptops/ROG-GL702VM/HelpDesk_Download/ download any programs you want from the Utilities section. From the Others section download Thunderbolt software and you may need to reflash so download the latest Thunderbolt firmware. Everything else I personally let Windows handle installing from Windows Update except Realtek Audio, Intel WiFi and Bluetooth drivers (you can let Windows handle these to I just like to have the latest drivers).
Now with the USB stick installed Hit the ESC key when booting to get the boot menu and select the USB stick and start the installation. Don't worry about needing a Windows key and if it asks for one just select Skip and when online it will activate.