Ring Wired Doorbell blowing transformer after two days in service

Hoping maybe @Sparky521 will see this. I’m about to go on my 5th transformer. I was suspicious of having the old doorbell chime remain in the circuit, so after the first transformer blew I disconnected the old chime and just used a wire nut to join the power wires together and the ground wires together. I have checked continuity on the wiring and suspected a potential short when pushing one of the doorbells wires (I have front and side doorbells) back into the wall. I have blown three transformers since then. The doorbells will work for two days, and then stop working. They are warm to the touch before I disconnect them, and they no longer put out any significant voltage.

One of the strange things I see on the multimeter when I measure the transformer connections (w/o the transformer connected) is a slowly climbing resistance up to about 120 ohms, and then going back down. I had been expecting around 50 ohms with one doorbell connected, and 25 with two connected. I have seen that before, but not consistently, making me think there’s a semi-broken wire somewhere. I still have to go and disconnect the doorbells to check resistance on those branches from where everything is joined in the box of the old chime.

I should note that the transformers have been 2 ring and 2 third-party, both 16VAC 30va, which ring claims is enough for two wired doorbells.

Any ideas?