No it doesn't mean they are all dead Monkfish. I'm reading Storey's Guide to Raising Chickens -an American poultry book which Tim recommended for recipies for mixing your own feedstuffs (where is Tim?). It mentions 'Power outages' -power cuts. Says trying to keep the eggs warm by wrapping them in stuff can kill them because of Oxygen deprevation. Just let them go cold. A power failure of 18 hours may delay the hatch by two days and significanytly reduce the success rate. An outage of 12 hours may not significantly affect the hatch, except to delay it somewhat. Outage early on makes the embryos go dormant. Later on they can generate some heat themselves to get them through it.
Now I have no first hand experience of this kind of timescale yet and probably never will, because we run our incubator with an inverter and batttery alongside it (4 hours is our maximum with the hen sitting on the wrong eggs). But Gail Damerow is highly respected in the poultry world with 50 years experience, so my guess is she knows what she is talking about. So get the hen back on them or get them in the incubator Monkfish and wait and see.