Garmin HRM 3-SS will connect/pair with forerunner 35 but will not show heart rate (see picture) - Accessories & Sensors - Running/Multisport - Garmin Forums
Support - Changing the battery on a Garmin Heart Rate Monitor
Garmin Fitness Heart Rate Monitors with Rechargeable Battery for sale | eBay
STL file GARMIN HRM3-SS heart rate monitor battery cover 💜・3D printing model to download・Cults