First a couple questions. Where did you try to feed your snake, in its viv or in a small deli cup? And what are the temps in your viv and where are the hides located?
There can be many reasons why a snake won't eat their meal. Sometimes they are just plain hard feeders and there is no seemingly cause except they just don't eat well. But, there are also many things that can cause a poor feeding response as well as many things to encourage a good feeding response.
First off, a hatchling eats best if placed in a small deli cup with their food item. Obviously, since you said the pink was proper size and warm, that would not be a problem. But make sure you feed in a small container so the snake has easy access to the food. Place the deli in a quiet, warm and dark place to encourage relaxation and desire to feed. Sometimes the snake will eat right away and sometimes it can take leaving the snake overnight with the prey item.
It is also best to feed at night as that is their natural time in the wild when they are active and eat. When the snakes are eating good and/or older, I find it makes no difference what time of day I feed, but when young and first eating, I find it works best to feed in the evening hours.
If you want to feed in the viv, place the prey item just at the edge of the opening to their hide (warm side) in the evening and leave overnight. This puts the food in easy access and the snake can grab it and pull it into the safety of its hide.
There are many other methods to try when you get one that becomes stubborn on eating. Instead of listing them all here, do a search using the search bottom above and query 'stubborn eater', 'snake doesn't eat', or similar types of queries and you will find lots of ways to try to encourage your little one to eat.
One thing you must make sure of is that you have proper temps and hides so your snake is not stressed. If the snake has the wrong temps, either too high or too low, or feels stressed, it will refuse to eat. So, make sure you have the probe type thermometer so you know what the temps are IN the substrate under the hide that you expect your snake to be staying in.
Also, it is good to let the person whom you purchased the snake from that you are having feeding problems so they can give you advice of how they were feeding this particular snake, and so they know in case you have further problems.
Best of luck.
