Guide :Exercise & Fitness : F11 Heart Rate Monitor
Polar F11 blank display
In the battery change I put it in the wrong polarity.My F11 is now in blank display.It likes to run, make bips, but can't light up running.The most intersting yet, it looks good when I reset it (3 buttons for 3 seconds)!!! It keeps very good characters until I press ok.Then, go blank again.What can I do (by myself) to fix it???Thanks a lot.