Default [Q] Unroot Sense 6

Hello. I've been trying to find a way to unroot my HTC One. It's currently just stock with TWRP installed. I didn't even root it, but I'd like to get it back to 100% stock to return it.

It's s-off with a locked bootloader, and I've tried running the 4.06.651.4 RUU but it get's stuck at "4% checking headers."

I don't really know what else to do, is there any suggestions anyone has?