The below instructions will help you to replace the cover on your sensor to address the tamper error.
You will also need to clear the error from the panel memory. Once the cover has been replaced, see instructions for GC2 GoControl - Silence Reset Trouble.
2GIG-FT1-345 Water / Temperature Sensor:
Align the cover over the sensor and press together, ensuring the top tab locks into place, to replace the cover.