I would try the following two things (along with what you're already doing) to see if they help:
1) Help him out by moving wires and other objects you don't want him to chew on out of reach.
2) Buy toys for him. Part of him chewing on everything may just have to do with him being bored! They sell wicker balls, sticks, blocks and treats that are made for rabbits to safely chew on. When he chews on these objects, reward him with a tiny handful of pellets or a carrot to reinforce the behavior.
Hope this helps!