Ive raised baby deer before. I suggest getting cow milk from your local feed store, warming it and feeding it to the deer with a bottle. Just feed it the same way you would a cow or goat. They are closely related to goats. So if you have goat milk that would be better.
However the BEST option to do is take it to your local wildlife office and give it to them. They have people that are paid to know how to care for the animals and they have the time to do so since its thier job. After a deer gets so old, it can become very dangerous to have around the house. Expecially if its male.