PSA: Look at the heart rate sensor of your fenix 5. Has it cracks like mine? If yes, it's a common problem. Send it to Garmin and get a free replacement. Do
Back Case For Garmin Fenix 3 3hr Forerunner 645 / 245 / 245m / 935 / D2 Sport Training Back Cover Replacement - Laptop Lcd Screen - AliExpress
Update: I had posted before about the cracking Heart Rate Monitor on my 5x. I contact Garmin and they replaced the watch. It was great customer. : r/ GarminFenix
Garmin Fenix 7 Sapphire Solar Titanium / Brown Leather Band (+ spare silicone strap) | Hodinky-365.com
The HR sensor glass of my FR645 is cracked and I don't understand why. I literally only take off the watch to charge it... Did this happen to anyone else? : r/Garmin
DIY HR Sensor polishing with home tools : r/Garmin
Back Battery Housing Case Cover Shell Repair for Garmin Fenix 3 HR Smart Watch | eBay