Sorry to hear you’re having trouble with your Mayfly logger power switch. That’s one of the parts I thoroughly test on each board before we ship them out, to make sure there are no problems with the switch. Occasionally we’ve seen them get flaky like that if the board has been in a moist environment (i.e. the inside of the enclosure was damp or had water in it), which causes some corrosion inside the switch that leads to poor contact of the movable parts inside the body of the switch. Sometimes all you need to do is cycle the switch back and forth quickly a bunch of times to break down the corrosion. But if you’re deploying a logger and you don’t want it to stop working sometime later, it’s probably best to replace the switch. You can just desolder the old one and install a new one. The part number is JS202011CQN and you can find it at a variety of online electronics suppliers for about $0.40.