For me, twisting the temp from one to five to one a whole bunch of times can often get it working again. I've also had luck with the iso soak up to the lights, but I sure was nervous before I did that one the first time. I've had it bring back a dead hopper though. I've also cleaned the threads on the back end and had that help. As well as using a really lightly soaked iso swab inside where the battery touches inside the unit to get that connection clean. Both my hoppers are in for service so I feel your pain of not having a working Hopper.