Glad it's working!
Dunno why everyone was talking about GPE conversion.. You never mentioned anything about having done a gpe conversion -_-
In any case, for future reference, USB debugging is merely a software setting for while in rom. It will not affect fastboot and Adb will work fine in twrp regardless. So if you have no rom installed, it doesn't matter if USB debugging was ever enabled or not.
Sent from my HTC One_M8 using xda app-developers app
: Telus HTC One M8: 3.16 HBOOT S-OFF
Exad's m8 Everything Explained Thread