Semantics of nanomachines

[Coolguye]

Does anyone have a good idea of how nanomachines work? Obviously, they turn you into a cyborg, but exactly how they do so doesn't seem to be very well understood. People who have eaten 5 Roburgers don't always turn, whereas sometimes someone gibs into a cyborg before they're finished with their first one.

Do you have to die while under the influence of nanomachines? Have a specific amount in your bloodstream while taking damage? Get blindly lucky? Anyone have any idea?