Hi, I had this issue before, however in this occasion also my time changed.
My Forerunner 230 is not paired with my phone, it stopped at some point and now is also showing the wrong time on it.
After changing the time manually it automatically change it to a random time.
I followed first time these steps thta were provided by Garmin first time I had this issue but not working now:
1. Go to your phone's bluetooth settings, and make sure the 230 is not listed as a "paired" device. The 230 should never be listed here. If it is, power off the 230, then unpair the device from this screen.
2. Download and install http://software.garmin.com/en-US/express.html onto your computer.
3. Attach the 230 via a USB cable to your computer and run the Garmin Express program.
4. Install any updates onto the 230.
5. Disconnect the 230 from the computer.
6. Launch the mobile app, go to menu > Garmin Devices >press the "+" icon on the top right
7. Navigate and press on the 230
8. Power on the 230, set the watch into "pairing mode".
9. In the mobile app, click "Search For Device".
10. Report your results please.
Could you please help?
thanks,
Aitor