this is what worked for me 24 hours of screwing with it...
mm2 dropping connections and clicks not working --after many restarts, safe mode housekeeping etc etc....turn off imac sierra and before it shut down 58 seconds delay...turn off power to mm2 let imac power down ...power back up when it does in cannot find the mouse cause it is unpowered and pulls up the bluetooth set up assistant aha, there we go. power the mm2 let it find it and walla connected..
mm2 dropping connections and clicks not working --after many restarts, safe mode housekeeping etc etc....turn off imac sierra and before it shut down 58 seconds delay...turn off power to mm2 let imac power down ...power back up when it does in cannot find the mouse cause it is unpowered and pulls up the bluetooth set up assistant aha, there we go. power the mm2 let it find it and walla connected..