Hi, my Lexus RX 450H from 2012 has the same problem. Sometimes the PBD works fine, sometime the back door open and and i here only two piep.
The battery was change for two years by my lexus dealer and my CTEK charger is every 3 weeks in use, because i installed a WEBASTO parking Heater.
An Idea? maybe Herbie can send me the file?
Regard from Germany, Frank