Is it glass behind the background? Are you able to see him behind it?
What you could try is making sure the front of the viv is covered and dark, put some extra small boxes around or small hides to lure him into one of those instead and leave a light on the back.
Just something low heat producing like an LED and not too directly onto the spot, but enough to feel too bright and make them want to leave.
Otherwise yeah, just wait him out. Sometimes if you have some dirty rat or mouse bedding you can leave some near the viv and the smell of prey may lure them out too if he does start getting hungry and comfortable enough to try exploring more. Then you can move him to a safer spot while rebuilding
Sorry you had to have this rough of a go but welcome to the adventure that is snake ownership!
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