Well, I just pulled a stupid beyond stupid.
I just flashed the recovery on my shieldc K1 (just updated to 6.0) using supersu.... instead of sideloading it in a moment of fat fingering. Luckily I finally got it to boot using the recovery.img from the base factory 3.1.1 image from nvidia (for the non K1) directly. Can anyone give me the recovery.img from the OTA for 6.0 lollipop? I can't figure out how to extract it directly from the OTA
You can use https://www.androidfilehost.com/?fid=24269982087005399 for the K1.