I've a HRM-Pro since one year and a half and I've needed to change the battery. Except that it no longer works, I tried with at least 4 battery, checked with a multimeter.
Why I say that it not longer works ? Because when I try to connect to my FR 945 or my phone, it is not detected.
Do you have this problem last weeks with your HRM-Pro ? What can I try to make it work again ?