Default HTC One M7 No ROM ADB error: device not found

So, I inherited this seemingly bricked HTC One M7. I wanted to fix the phone and possibly flip it for a profit (since it was free and all), but I haven't been able to find a proper solution to the problem of this phone. Here's the skinny:



I'm using Windows 8.1 and think that most of my problem is stemming from the recognition of the device. I can see the device listed as "One" under other in Device Mgr, but when I downloaded the Win 7 drivers (per a guide I can't seem to find right now), Windows did not recognize what I was pointing it to when attempting to update the drivers, so the device remains unrecognized by Windows.

Fastboot commands work, but ADB commands will not work as the device is unrecognized?

The phone has no ROM. Factory reset from bootloader simply returns the bootloader screen and accomplishes nothing.

The phone currently has CWM recovery, but both CWM and TWRP are unable to mount /system /cache or USB. I was also unable to find any install .zips or backups in the recovery module.

The phone has the *TAMPERED* and *UNLOCKED* flags above the versioning in the bootloader and lists S-ON.



I've tried several approaches to fixing this phone, but each method seems to rely on some other step I can't complete. I've reached a stalemate (checkmate?). I'm not sure whether to be hopeful with this phone or not, but I'm going to be anyway. If anyone can offer me some help with fixing this thing, I'd greatly appreciate your time. Thanks!