Ring2 doorbell shorting out transformers

I have had hardwired my rings for many years w/o any issues.  I recently purchased some ring2 units and they are shorting out the transformer after operating fine for a couple weeks.  I do not have any chimes.  The rings are wired directly to the transformer and nothing else (just like I’ve been doing for years).  After i noticed the dead transformer, I measured the resistance of the wires and there were no shorts in the wires. I then measured the resistance across the 2 screws of the ring and I got 15 ohms on the bad ring and 80k - 100k ohms on all the good rings.  So the bad ring is drawing lots of current and eventually killing the transformer.  This has happened twice.  Im wondering if there is a bad batch of ring2 doorbells that develop a soft short in the charging circuit (15 ohms is a boat load less than 100k ohms).  Anybody else run into this issue?