Doorbell 2 (2020) continuously ringing

I just bought a Ring Doorbell 2 (2020 release). I hardwired it to my existing doorbell (with a 8-16v transformer). When I switch power back on, the digital door chime (Friedland E821) continuoussly rings.On the phone app, during set up, I selected hard wire but it could not detect any power input. On device health, power source still shows "battery". I manually changed the type of chime (digital 1 or 2) but it made made no difference.On the Ring product spec page, for 2020 release, it says no resistor and no diode required for hard wiring.Does anyone have similar issues or can Ring advice. Their phone in help line is useless, still on hold after an hour.