Some babies need to be harassed the get them to start eating. It sounds this baby has already been eating and then quit. Baby snakes dont eat and then quit for no reason. There is an issue. My guess is dehydration as that is a very common issue with neobate GTPs. It also leads to prolapse which is why you see a lot of neonate GTPs prolapse but almost never see adults prolapse. Adults have much more mass and much more body liquid. Babies dry out really fast which can lead to a downhill spiral really fast.
I personally would not assist feed unless it was a last resort. If the snake is dehydrated to the point it wont eat and you shove food into, you are asking for a prolapse or a regurg and then even more issues. Now as the last resort, you can assist feed and inject the feeder with a nice amount of unflavored Pedalyte to replace liquids for it but again, i would start off with offering it a bottle cap of water to its face and see if it drinks. If it does, do that every day for a week and then offer it some food as well as making sure you have elevated water bowls next to its favorite perch spots.