Stewe N Sammy

My son who is 21 lives in the Uk came out last year on a 18-30 working holiday visa but only stayed for 3 months. In that time he did not work but had to return early to the UK due to family comments. He is now wanting to return but that visa has expired. Does anyone know what his options are for him to come over and work over here in Oz? He does not have a skilled trade so he cannot apply under a skilled trade visa. Any advice would be helpful ?