I hooked up the im608 to 2011 S4 with all keys lost and the BCM2 went dead. I have a replacement BCM2 coming but I like to find a way how to bring those bricked modules back to life.
I think on the bottom of all that is the fact that the battery was at 11 volts when doing it. Before I went there I asked and the owner said the battery was charged so I didn’t get jumper cables and was definitely a mistake I made.
I lost communication with the BCM2 in a 2011 S4 B8 from what I think was caused by a weak and undersized car battery. So first of all you make sure the voltage is good, in my case was 11.4 V.
It looks like the BCM2 was stuck in boot mode and no communication was possible with ODIS or vcds or Autel.
However, the mighty xhorse vvdi2 did the job.
I used abrites “vag force tool” and started the process of learning a key under 5th immo system AKL.
After that just followed the instructions on the screen and that was it. Everything went smoothly and I have adapted 2 keys.
This time was too easy, I hope this will help you if happens to you in the future.