reboot and poweroff fails on Zotac ZBOX Nano CI320

[Jesse Molina <jesse@opendreams.net>]

Hi all

I have a new Zotac ZBOX Nano CI320. It's a mini-PC based on an Intel 
Celeron N2930 (Bay Trail).

This has been a very problematic system. I blame my troubles on the 
less-than-quality Zotac (AMI) BIOS.

My current problem is that the system will not reboot or poweroff 
correctly. It just hangs.

I have upgraded the BIOS to the current version, which fixed a lot of 
other issues, but not this one.

I've confirmed this bad reboot/poweroff behavior on Debian 8.1 and the 
current unstable. One thing to note is that I was having some 
intermittent success adding the kernel argument "reboot=bios" on Debian 
8.1, but now that I've upgraded to unstable, it's not working any more. 
I need to do more testing to verify what works and what doesn't, but 
everything is mostly not-working.

I also confirmed this bad behavior with the current Fedora release.

Interestingly, the current Linux Mint seems to reboot and poweroff normally:
http://www.linuxmint.com/edition.php?id=172

Other than testing various linux "reboot=" arguments, what other things 
should I look into?

For permanent application, that reboot= would go into /etc/default/grub, 
right?

Any other advice before I bug this?

Thanks for reading.