Hook up bluetooth antenna to an Arduino (Or similar)
This PWA does not have a true ELM327 chip but there is a Microprocessor under the black CoB blob. This is (more than likely) a copy of the ELM327 v1.0 software with the version data changed to spoof a later version (ELM did not copy protect their first version of the software, but did in later versions after someone copied out their code). The connections would depend on what you are trying to connect to. There are 2 TX/RX sets, one is after the 8 pin chip as it converts the Vehicles CANbus into RX/TX for the ELM327 clone, the other is the data from the ELM327 that is being transmitted and received from your Bluetooth device (this I suspect is actually I2C and is on the 2 traces that go from the black blob to under the BK3231.