You should know that force-feeding an axolotl is not opening its mouth and stuffing it with pellets! You can just wet some pellets with water from the tank, grab your axolotl with a clean soft cloth and try to feed it with a syringe but without forcing it too much if it continues to regurgitate this mixture. Force-feeding is not recommended and it is best to find out why your axolotl refuses to feed and act accordingly. But you can try to encourage your axolotl to eat by exciting him a bit more to trigger his predatory instinct. Some axolotls like live food more than dead prey or pellets, so you can bring the worm or piece of meat to life by waving it in front of its eyes.