This seems to happen a lot to a lot of people, happened to me yesterday. You need to connect your polybrute to a computer running Polybrute connect. Polybrute connect will tell you that the firmware on your machine is 0.2.0 (for som inexplicable reason), and that you need to update the firmware. Once you have updated the firmware the synth works fine again. I was pleased at least to find that my custom presets where not lost