I'm assuming you are handfeeding the chick, and the food must be warm in order for it to move through the digestive system properly. If the food is cold, it will sit in the crop and cause problems (crop stasis). Just as you would have the formula warm for a human baby, not too hot and not too cold, you want the same for your finch baby. Also, if the brooder or nest you are using to keep the baby is not warm enough, the crop will not empty. The baby should be kept at a temperature of about 92-94 degrees F if it does not have feathers yet. Here is a link to an article about handfeeding:
http://www.finchinfo.com/breeding/handfeeding.php
And welcome to the forum! There's lots of good reading at the Finch Information Center, linked at left, and the members are always ready to answer questions. If you put your general location in your profile, it makes it easier to answer locale-specific questions later on.