Question [Q] [QUESTION] Flashing stock recovery

I'm trying to set a up a device for a relative of mine who, whilst not the most tech savvy of people, has a habit of breaking things accidentally and likes to push buttons. I've boot unlocked their device, flashed on a custom recovery and rooted their device for them, but when trying to stick a stock recovery back on (as a .img file) I keep getting a "Preflash validation failed" error when I fire off the flash command from Moto-Fastboot.

Has anyone got a version of the KK stock recovery that works via this method or who knows of a guide to doing this (preferably via the moto-fastboot or adb tools as I'd rather not install anything else on my laptop)?