Does he take toys to bed with him Jess? We let Ella choose her teddies to go into bed with her at night - believe me changes every night. And it is not just one or two - often about 15
What about leaving a hall light on to soothe him - might just be the newness of the bed.
When we moved Ella over to the toddler bed, she often wandered about but it was just because she could - somehting she had never been able to do in the cot. It could just be a comfort thing and the sudden amount of freedom is frightening him
Does he take a dummy? we made sure not to take everything away at once. So it was bed, but she still has her dummy at night ( we went through a spell where she needed 3 or 4 with her, shortly after the twins were born - one in each hand, one in her mouth and one in her shopping basket as a spare. Don't ask why she takes a blo*** shopping basket everywhere with her
What about even letting him choose his own duvet cover etc?
Other than that hopefully he will accept his new bed soon and sleep through the night so you both can get a sleep