Here's how I made it work:
- Take the battery out of the HRM
- Use a small screw driver to touch the two battery contacts at the same time.
- This shorts out the power and drains any remaining charge in the unit
- Insert battery back into the unit and attempt to pair with your application
- Note that the H6 and H7 won't pair with the iPhone directly; they need to be paired from within the application that will read their signals.