Bootcamp No Bootable Device Found

So, I have been trying to install Windows on my girlfriends Macbook Pro 2012 with Mojave as well on the other half of the drive. So I used Boot Camp Assistant using a USB device and finally got to the part where you partition the drive and you allocate space for the partition. It then rebooted and then a black screen with no bootable device... press any key to continue type of thing. I did some research and this is where it was suppose to boot to the windows side but it did not do that. The Mac side boots fine but just trying to figure out how to finish this process. I tried to do the commands from other people with similar problem from responses with LonerT but I didn't get too far as I really have no idea what I'm doing when it comes to the Terminal.