Flickers and building on the idea of nanotech as possible mechanism

I went back and watched the first two episodes of Season 1 over the holiday and noticed the mini power surges where lights flickered in town before the initial resurrection event.

So building on my earlier theory about nanotech being a possible mechanism for reanimating dead/inactive cells, maybe the nanotech operates on a type of current that is only good within a grid or circle of power stations and once you leave that grid, they cease working and the reanimated, revitalized tissues decompose rapidly because the nanotech is the only thing keeping the pervious dead cells active.

Think about it. Cells are biological programs. If you can get a long dead computer to reboot and turn back on, it would immediately start accessing it's files and programs. Perhaps whatever technology Noregard is using, it works in a similar manner.

A modern day take on the whole "Frankenstein's Monster" concept perhaps?

Oh, and the boatman's whistle. Perhaps the nanotech/nanobots can only get turned on by a certain sound frequency. Perhaps the Doctor dropped the whistle at John's gravesite when she accidently reanimated too many of the dead. She was certainly looking for something when she "discovered" the whistle. Seems too coincidental to me.