Hi Duncan, hoping things have improved but wanted to chime in to clarify something - Peter is taking it that you are trying to add your swarm capture to an existing colony, which is why he suggested the newspaper method. I am wondering if you are talking about installing your swarm into a new, empty kit? If so, no newspaper is needed and might be more off-putting in this case.
Assuming your kit is brand new and your bees are still there, see if you can find a local beekeeper who will donate or sell you a frame of brood to put into your box, and/or some beeswax to rub onto your frames - these will make your box attractive to your bees, especially the frame of brood which nearly always succeeds in inducing a cluster to cover it and start taking care of the young larvae in open cells.
I am curious if you used any type of finish on the inside of the box that’s possibly repelling to the bees, or if it’s become wet with condensation inside? Anyway, send an update if you can!