Just to clarify when you press the rear ‘join’ button on the back of the Arc and are powering it on - are you continuing to hold-in the join button and making sure it’s continually pressed, until you see an amber flashing status LED?

If yes, then how many times have you tried the factory reset procedure? How long did you hold the button for?

Yes, I pressed the button for more 10 sec while attaching the power. I tried this 4-5 times .  Only white light on right side is on. 

Are you able to try the process again with the Arc wired… I think you may need to hold the button pressed for longer than 10s - Anyhow I guess we can’t rule out that the Arc maybe faulty at this point, so if you still have no joy, then perhaps go onto speak with Sonos Customer Support. Here is the link to contact them:

https://support.sonos.com/s/contact