I am guessing that a jet turbine engine pulls in more air than is needed for combustion because the extra air keeps the fuel-fed burn away from the sides of the combustion chamber and therefore reduces the heat load on the expensive shiny bits. When the battery is down on power the starter generator does not reach the required speed so the volume of air pulled into the combustion chamber is below the designed flow and the burn is not kept away from the expensive bits, which then overheat and stop being shiny.
You can probably tell from the technical language that I own / drive them but I don't build or fix them. Hopefully someone will be along shortly to provide a better explanation.