So I've heard that if you add dead yeast it can serve as an nutrient for the rest but I read in an wikipedia article on stuck fermentation that "Once the fermentation is stuck, it is very difficult to restart due to a chemical compound released by dying yeast cells that inhibit the future growth of yeast cells in the batch."
So do dead yeast cells "sabotage" the rest?
Maybe it depends on how they die. Quickly in boiling water, or slowly in a must. It's pretty common practice to use dead yeast, it's an ingredient in LD Carlson's Yeast Nutrient, and many other yeast nutrients on the market.