Well, according to Gigabyte, the GNC-C30 is no longer available. Their play here is to install the 15.2V GNC-J40. It does sound like they will need to install some sort of voltage converter or something ("there will be some soldering involved"). And they won't release the spec of the board for DIY purposes. So, while I'm loathed to send my laptop in to them, it sounds like there isn't much choice.
For what it's worth, they have confirmed that the GNC-J40 won't obstruct the 2.5" drive. But in lieu of soldering iron and the technical specification of the laptop, I wouldn't try installing it. I tried chasing this up via my original reseller and they have come back with the exact same thing: GNC-J40, send it to Gigabyte. If there's an alternative at this point I'm not sure what it is. Sorry I don't have better news.