A kinked cord can cut off the flow of oxygen to baby so while it may not seem like a good answer, there really wasn't anything they could've done except deliver her early and she might not have lived anyway as she was so young.
My heart breaks for you and I'm so so so very sorry for your loss.
I know someone who had an ulttrasound in the morning and her baby died that afternoon because of a kink in the cord...she was 8 months pregnant and knew within hours due to loss of movement.
As hard as it is for your daughter, sometimes this just happens
Sometimes they can't see kinked cords in ultrasounds, and it can happen within a few days that it becomes a problem. Kinked cords aren't common at all, and it was most likely simply chance that it happened, I'm sure it doesn't make it any easier, and I hope this doesn't prevent you from having more children. Message me if you need to talk or anything.