No doorbell wiring, just want camera

I want to install the xfinity doorbell camera only. There’s no previous wiring. I bought a 16-24 VAC plug-in transformer and just hooked up the two wires directly to the doorbell. It worked for 30 minutes and then went dead. Will not come back on. The voltage meter shows 27.4 VAC. I unplugged it for a day and plugged it back on. Still nothing. I wanted to replace my Geeni doorbell camera, which was wired directly from the transformer’s two wires also, with the xfinity doorbell camera. I hooked the Geeni back up and it’s working fine. The xfinity is DOA. My question is can the xfinity be wired directly to the transformer with no chime and chime kit not being used? It didn’t seem to last long, where the Geeni has been working for months.