Boot repair fail, partition strategy

I bought a new laptop yesterday, a MSI GS60 Ghost Pro-002 with a Core i7 (6700HQ 2.60 GHz) and an Nvidia Geforce GTX 970M, 128GB SSD and 1TB HD. Came installed with Windows 10 obviously, and for the sake of trying, I figured I would dual boot this machine instead of wiping Win10 off completely. I got last nights build of the amd64 install of 16.04 and got it installed to a few different (new) partitions. After installation, no grub menu, boots to Windows. boot-repair utterly fails, but I ultimately fixed the boot order in BIOS settings.

After the install completed, the laptop rebooted, and went straight to Windows, no GRUB menu appeared. When I was doing the installation, I chose custom settings, because I wanted / mounted on a SSD partition, but I wanted /home mounted on a new partition on the HD. It asked where I wanted the boot installation, and I chose the SSD device, but not a specific partition (wasn't sure what the best option was tbh). So I was able to pull up the boot menu by holding F11 at the MSI logo before Win10 launches, and choose the ubuntu partition, and launch GRUB. I figured the smart thing to do would be to install and run boot-repair. However, it would always get up to the step that says "Unhide boot menu. This may take several minutes" and effectively hang. Progress bar stopped, and I couldn't even open the System Monitor to see what the CPU was up to. In the end, I fixed it by going into the BIOS and promoting the Ubuntu partition above the Windows partition. Although this fixed it, I don't understand why boot-repair failed.

I wasn't sure about my partitioning strategy, especially since Win10's is so complicated to begin with. But I basically carved out about 24 Gigs of the SSD for the root installation, and about a third of the HD for the ext4 /home mount partition (and another 4GB for swap). In case I decide to factory reset and reinstall Ubuntu, is there a different partition strategy that I should try? Is there any way to diagnose why boot-repair failed to work? Thank you.