IMHO you are better off monitoring your resting heart rate trends - the heart rate sensor in the Fenix 5 Plus is VERY good for measuring resting heart rate, and is within 1 BPM of both my Wahoo Tickr and Polar H10 heart rate belts.
You can update your gender, birth year, height, weight, heart rate zone, and power zone settings. The device uses this information to calculate accurate training data. Hold MENU. Select Settings > User Profile. Select an option.
Turning Off the Bluetooth Smartphone Connection. Hold LIGHT to view the controls menu. Select to turn off the Bluetooth® smartphone connection on your fēnix® device. Refer to the owner's manual for your mobile device to turn off Bluetooth wireless technology on your mobile device.

Body Battery is one of Garmin's best features - find out all about it here, including how it works and what exactly your score means. Garmin Fenix 6 series ; Garmin Forerunner 45 / 45S, 55

KIMILAR (3 Pack compatible with Garmin Fenix 6S / Garmin Fenix 6S Pro/Garmin Forerunner 745 Screen Protector, Tempered Glass Cover Screen Protector compatible with Huawei Watch GT Smartwatch £7.99 £ 7 . 99 (£2.66/count) If fail: Even if out of warranty, I'd call Garmin Service, for advice and to get the price for out of warranty repair. Next I'd try to get some better arrangement. If fail: (I do not advise this, it's just what I would do) study videos of people repairing a Fenix 5 Plus, get the tools and isopropyl alcohol ready, check inside if anything is MCv7L. 870 244 666 992 696 161 693 25

garmin fenix 5s plus body battery