had exactly the same issue of B&O logo boot loop on jukebox. Changed battery but same issue remained. Close to be using the jukebox as a wooden tray. After a bit of search came across the post in here https://www.reddit.com/r/BangandOlufsen/comments/rwpr1l/beosound_moment_firmware_issue/?rdt=62235
where you short circuit the Vol-(+) GND and RESET GND pairs simultaneously (I just realised that the post by guileukow above is exactly what I refer to).
Had tried the same before but not been successful. Tried the same again trying a couple of times selecting different pairs (i.e, Vol- GND and RESET GND vs Vol+ GND and RESET GND) and ...jukebox went into reset mode (see attached image). After a couple of minutes was back on initialisation page and now functions as when bought.