This is just for info if you have problems resetting your Play 1.
Had to reset my 2 X Play 1.
According to Sonos' instructions, you had to press play/pause down when connecting the power cable. After that it started flashing white, then white and orange and then it should flash green after some time and then they should be reset.
(They have previously been connected to wifi and part of my surround set)
Mine would never flash green, they just flashed white and orange forever. Therefore, I could not connect them again. And believe me I've tried everything :)
Found the solution on this page through a lot of searching.
Connect your Play 1 with a network cable to your router, power on your Play 1 while holding down play/pause, wait until it flashes orange and then you can release.. After approx. 2min it flashed green. Now I removed the power cable and internet cable and placed it where I wanted.
Connected my Play 1 to power, after 1min they flashed green and then could add them to my system via the app. And then add them to my surround setup.