We are about to release firmware 2.1.8 (the firmware file is ready, still finishing up documents etc). You can download the firmware here:
https://github.com/OpenSprinkler/OpenSprinkler-Compiled-Firmware/tree/master/v3.0
2.1.8 should trigger a full flash memory reset which should eliminate the reboot cycle problem. @marc2: if your controller went into reboot cycle, you will have to upload firmware through microUSB port. I see that you have submitted a support ticket and will continue the conversation there. In order to upload from USB port, I need to know your operating system (Windows, Mac, Linux?) so that we can send the appropriate firmware upload tool.