Sounds like he doesnt trust you yet and wants to stay where he thinks it's safe.
Dont force him, leave him alone and let him come out in his own time and under his own terms.
If you have a plant or fake tree or something like that, you can open his cage door, put it up close, and wait.
He will get curious and climb out and into the plant.
You can then gently move the plant, with him in it, out of your way and clean the cage.
Only thing is.... good luck getting him back inside if he is already not inclinded to want to get on your hand.
You may have to use a stick, and cross your fingers he doesnt think it's a snake