Currently I've been attempting to install Fedora Live Robotics spin to my USB drive is livesusb format. I didn't want to take up all of my drive space for the OS so I partitioned the USB like so:

/dev/sdg1: NTFS 6GB -->mounted at NAH
dev/sdg2: FAT32 2GB -->mounted at /media/iso

I then used the Unetbootin program to install the iso that I downloaded to the second partition of my USB. After the insallation finished I rebooted and tried to boot via USB and I got the "Bootmgr is missing" error. I'm not sure how similar syslinux and grub2 are and I wasn't sure how to work with syslinux given that I'm more familiar with grub2. So, I reinstalled the iso (after wiping the second partition) using the dd command instead. I then installed grub2 on the USB using
grub-install --root-directory=/media/iso /dev/sdg
Then I went to my /etc/grub.d/40_custom file and added these lines:
menuentry 'Fedora Live Robotics'{
        set root=(hd0,2)
        chainloader +1
Then I went and added the config file for grub.
grub-mkconfig -o /media/NAH/boot/grub/grub.cfg

Finally I booted from the USB selecting the menu entry i added in the grub2 menu....and I'm still getting the BOOTMGR error. The Iso file is not corrupted because I tried the install from the 1st partition and it worked fine.

Help would be awesome - my main task is to install the os to the second partition and be able to boot from it. Thanks