It is the black clip plugged up and into the white box covering the door lock mechanism in this image:
Sorry for the delay in posting, as soon as I'd posted about it yesterday I tried again with a multitool & cracked the piece of plastic serving as a clip on it, risky I know but it was getting replaced anyway, and pulled it off easily then.
That one and the black cable connecting next to the white part below were the two toughest to get to pull out. Then again they hadn't moved in 6+ years.