KY-42C original boot.img backup

Hey, I'm returning my KY-42C and replacing it with an A202KC. I had previously rooted it. I've unrooted it now, but I didn't back up my boot.img (I was using mtkclient on a live USB, I learned my lesson) so I can't lock the bootloader as whatever image is currently there isn't verifiable. Does anyone have the original factory boot.img?