If this was an adult, I wouldn't worry; however, hatchling burms are typically eager feeders and they usually need a month to acclimate. You mentioned your temps/humidity levels are fine; what are they? There is so much awful information on the internet (and from forum contributors) that I cringe when I read half the stuff that is out there. Give us some specifics: temp on warm end, temp on cool end, humidity level, ambient air temp, etc. Are you providing a hide area on both sides of the cage? If so, I would highly recommend that. Keep your handling to a bare minimum until the snake is feeding regularly. Try feeding when the snake is in its hide area and offer a f/t and rewarmed adult mouse on long tongs. I usually like to slowly wiggle the dead rodent in front of the hide entrance to elicit an abmush strike. For a stubborn feeder, I will do this at night or when the lights are greatly subdued. Hope this helps.
Rob Carmichael, Curator
The Wildlife Discovery Center at Elawa Farm
City of Lake Forest Parks & Recreation (IL)