Garmin HRM-Dual not working

Have tried this twice now after battery replace (with two different batteries). Edge 530 sees it, but never connects..  Going to shop some other brand HRM now. 

Bought a Polar and it just keeps working like a charm. Connects instantly, even to multiple devices at the same time with no issues at all.
A true delight.

Ultimately the HRM-Dual didn't work for me after all, so I purchased the Garmin HRM-PRO + and have had zero problems with it using both an Edge 830 & Forerunner 745.  In fact the running metrics it provides are terrific.  

Adding a new battery did not work for me.  It wasn't until after I did the reverse polarity reset did it finally connect and work fine.

I had the same problem. Android phone Bluetooth finding the sensor but not transmitting data. Solved the problem by resetting Phone's Wi-Fi, mobile networks and Bluetooth (search this action in phone's settings)

My HRM not working 

So happy this worked (flipping the battery) was just about to buy a new one. Thanks. :-)

Just to be clear, flipping the battery didn't help in my case.

Bought an HRM-Dual together with a Concept2 rower. Ant+ module works fine, but the BT module connects but won't send data. And this was out -of-the-box, Day 1 of ownership. Day 2 of ownership was spent at the local service center, figuring out the issue. Managed to confirm the BT module of their demo unit connects to Polar Beat (connects + transmits heart rate data), while mine connects but does not transmit heart rate data. Regret buying this over the H9 I wanted to buy (wasn't in stock). Had bought the dual anyway thinking I might buy a forerunner in the near future - well, forget that. RMA'ed the dual through the original vendor (service center said they might need weeks to sort out the replacement due to mine not being a local unit), but went ahead and bought a polar. When the dual is replaced, I'll keep it as a spare or sell it. My advice? Avoid this product.