Well I see from your other posts you have been digging around. I think Unknownforce's ultimate downgrade tool thread is your best bet. It will work. And yes it does require Linux, but you can download the liveCd version which includes the needed Linux os. You just copy it to a bootable CD/thumb drive and boot it temporarily. If I recall you have do the "brick" the bootloader step twice for it to work which as I recall someone documented in Unknownforce's thread. Once you get the Main version and bootloader downgraded you will be able to run an earlier ruu for s-off or unlock.
Sent from my Up all Night Sleep all Day Nexus 5!
Sent from my Up all Night Sleep all Day Nexus 5!