Researched this issue on SONOS community and after doing everything suggested ROAM still flashing green and saying getting ready to connect to existing system but after 30 minutes still nothing and powers down. After 5 goes something wrong.

Reached out to customer support 3 times via SONOS website and always no-one available. 

SONOS used to be better than BOSE but sadly they have failed customers. Funny thing is they reach out to get more product sales whilst at same time providing no customer support.