Because of frost damage, I pruned all the fronds and new ones have not grown except at base. The top looks like a rooster tail...picture attached. Any advice?
You will need to remove the brown fronds or parts of fronds this spring but only those, as they will not come back. Do not remove green parts of fronds. These articles will help you as well: https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm
This article will help with wintering your sago in the future: https://www.gardeningknowhow.com/ornamental/trees/sago-palm/sago-winter-care.htm