[Q] M7 Htc one - Return to stock topic

I hope one of you kind people can help. I have a HTC one M7 which I need to return to stock to get a warranty repair. It has been s-off'd (?) and is running hboot 1.55 on an ORANG001 cid. I have tried to restore a CWM nandroid backup (which failed) and I don't seem to be able to find an RUU for my CID. Can anyone help with this please ? All the posts I have found have been outdated, or relate to different CID's.

Thanks in advance,

Andy