This ended up having Fanuc tech support scratching their heads too. We think we have it partially figured out; my company bought this robot (and later, the J567 option) from an integrator who apparently mated a M710iC arm (originally with an R30iB controller) to a R30iA controller (originally with an R2000iA arm). Somewhere in there, the integrator messed something up - the Fanuc rep said that R30iA requires a reburn for DCS so he doesn't even know how they generated a PAC code for it. Of course since we went through an integrator Fanuc can't help me directly, they have to deal with the integrator who isn't returning calls or emails right now.
So in short, the PAC code didn't work because you can't install DCS options on an R30iA controller with a PAC code.