UK FR235 user here. So my HR sensor died. I'm on software version 7.4. Went for a run on the Saturday - HR logged ok. At one point on Sunday I noticed the watch had turned itself off. Turned it on. I realised that there were no green lights coming from underneath. Checked the settings->system->about and the WHR firmware version was showing as 0.00 (0.00.00). Tried various things: turning the HR sensor off and on. Turning the watch off and on. Resetting to defaults at the advice of Garmin support didn't have any effect. I was advised to send in for out-of-warranty repair (the watch is four months out of warranty). Estimated repair cost at Garmin: 85.16GBP. I wasn't happy - 16 months of use for something that cost me 230GBP.
Thought I would try a hard reset. I read that this involved holding down the two right buttons after holding down the power/backlight button. I'm not sure that I did this right but as it was booting back up I held those two RH buttons down until I got bored (screen was just showing the Garmin logo throughout). I'm not sure if this hard reset it or not as I didn't have to turn off the confounded button beep when it had finished booting (i.e. my settings were retained c.f. a reset to defaults)
Happy ending though - the green LEDs are shining again and the HR sensor is back in action! I thought I would write this up in case it saves anyone else 85 quid! Honestly this device has periods of exasperation for me...:mad: then long periods when it works just fine! :cool:
So moral of the story - try this hardware reset if your HR sensor mysteriously dies.