What an annoying problem…..
I don’t claim to know anything about GDI’s or electrickery. But would hazard a guess that with the loss of the instrumentation and with Pemlar’s OBD reader not connecting, it may be that the CAN-H and CAN-L signals from the ECU to the BCU have disappeared, or become intermittent. The connectors on the BCU might be something to check as it doesn’t take much muck or corrosion on these connector pin to lose a signal. If it was mine I might first disconnect the battery and then re-seat the BCU connectors a few times, along with a squirt of contact cleaner to clean the pins.
There’s a GDI BCU pic in this
thread. Good luck
