Bluetooth does not appear in System Extension

System Information reports “No information found” for Bluetooth.

I have replaced the bluetooth board. I have replaced the cable from the board (+ camera, + sensor) to the motherboard. I have confirmed the camera still works. I have carefully replaced the aluminium foil over the exposed cable shielding.

I am presently starting up the machine with no display and using an external display (just in case this information of of use).

The logic board has been out of this machine.

Any advice on what else I should be looking at to determine the cause of this bluetooth fault?

This is a tale of two second hand iMac's. The first one came without an LCD display, had been spray painted green with a hole drilled in its base. It needed RAM, new display, glass, HDD, some screws etc. [I had noticed later that the microphone cable had been cut] Clean OS install and done. Needless to say the Green spray tan was somewhat ugly and I kept an eye out for another iMac (exactly the same). I picked up one without a logic board or screen... I then transferred the contents from the Green iMac to the shiny silver one... First boot and everything is great!... Camera works, microphone works... WiFi works... it wasn't until sometime later I checked bluetooth... it wasn't working ... I have since replaced the bluetooth board with the one from the Green iMac, and also a new one from China. I've also replaced the multi part cable connecting the bluetooth board and camera etc... and put in new silver tape. (why is the cable exposed in two parts anyway? - separate question]. Hope all that makes sense...

Finally... I'm currently starting the machine up without the LCD panel in. I'm running off an external monitor. Yep the fans go crazy because of the LCD temp sensor fault (it's not connected). I wouldn't have thought that would make a difference for bluetooth.