Strange conure behavior. What do i do?

Im babysitting my boyfriends green cheek conure. He hatched september. He acts very scared and its almost impossible to persuade him to trust you at all. He wont step up to get out of the cage. And he runs from you when you try to get him to step up out of the cage. Yet he doesnt bite at all when you handle him. Im not chasing him with my hand or anything i just move and he takes off. I think the people and dogs my boyfriend lives with have him so scared he doesnt wanna trust anyone. ive babysat him before and he was a lot more trusting out of the cage but this time he acts way more scared. He also does this weird thing in his cage where he'll hold onto the side of the cage by his beak, with his feet just dangling and he twitches and shakes his wings? Does anyone know what this could mean? Or how to persuade him to be more trusting. He's such a sweet heart. Ive never had a bird not bite at least once but he doesnt even try to at all. I wanna do whatever i can to make him more comfortable. Help?