connect Kindle <-> PC with USB cable.
Run Wireshark on PC (Wireshark can monitor USB ports as well as network ports).
Step Kindle through all of the actions you can think of - see if any of them happens to start something useful, like ADB (The KOA2 is one of the "Androidized" models).
I.E: Pretend you are exploring an Android device (which it is, at least in part, the parts that run early, before switching to the Amazon/Linux system).
Note: Wireshark is available for all common PC systems:
https://www.wireshark.org/download.html