I've had this problem with my Camry Hybrid 2007. My aux battery failed last winter. I replaced it the Toyota OEM battery and it has been failing since December. Does the DCM update affect older models too?
I had concluded that a parasitic drain was causing the problem and wondered whether the ECU was continually trying to communicate with the Bluetooth pressure sensors in the tires, which have reached their end of life, even when the ignition is off. I didn't want to spend $700 replacing the sensors as I can check the tires regularly and top them up anywhere with my portable pump. Other potential parasitic drains could be from a faulty touch sensor on the door handle, the trunk latch not turning off the light in the trunk, or a faulty fob switch constantly communicating with the car (one of my fobs doesn't work.)
