Ring Doorbell 3 hardwired not charnig

Hi there ! I bought a Rind Doorbell 3 which I hardwired with a AC 20V 2.3Amps power supply. I’ve added a 50W 25Ohms resistor, between the power supply and the Ring. I’ve tested directly on the ring : the voltage is 19.6V so it is hardwired. But on the app, "Power source" is still "Battery". It won’t change for "Hardwired"... So, of course, the battery is always going down and never charging. The support phone number given on the website is wrong (00 800 87 00 97 81 or 0800 87 00 97 81 do not exist) Any idea ?