Okay, I managed to fix this problem. For anyone in the future with a similar problem, that's what I did:
1. Download Kubrick ISO
https://www.mobileread.com/forums/sh...d.php?t=206064
2. Extract/mount the ISO
3. Navigate to KUBRICK\RESOURCE\DEVICES\K4
4. Extract FASTBOOT.SFS
5. Extract diags_partition
6. Copy the directory etc\upstart
7. Transfer it to the Kindle where it belongs
8. Change the permissions! (in this case I made them executable)
Thanks ixtab and the forum for all the amazing resources!
Have a good day!