Put something across the bottom of the door so he can't get under it (assuming he's still in the room). Then set up the bucket trap. Some people have had success with human mouse traps as well - maybe easier with a robo.
https://www.amazon.co.uk/Pest-Stop-P...ane+mouse+trap
If you use one of these, put some hammy chocolate at the very far end - as far back as possible - otherwise they can reach in and wedge the door open while taking the treat!
I think someone else suggested putting their wheel out as well, and maybe put some food in the wheel. Do all three!
What cage does he have? You could use the cage as the bucket trap - that worked for someone recently. Put the cage near somewhere he might be (eg under a cupboard or somewhere else where it looks dark. Set up the pile of books or magazines next to the cage leading to the door and a trail of food up the magazines and some tasty veggies and cheese inside the cage. He might just end up back in the cage. If the cage has a top door, set up the magazines to go to the top of the cage and one along the top up to the door and a nice deep pile of substrate under the door with nothing hard to fall on, and the veggies etc near the pile of substrate - so he might jump in to get them.