Moved to the root forum.
Yeah, you used an out of date guide too.
Get the Mini-SDK -
http://androidforums.com/threads/adb-guide-updated-2014-11-11.443072/#post-5389081
Unzip the sdk-tools.zip file, you'll get the sdk-tools folder.
Windows Explorer, shift+right_click on the sdk-tools folder, choose Open command window here.
Get the latest TWRP -
https://dl.twrp.me/m8/twrp-2.8.7.0-m8.img.html
Move that to the sdk-tools folder. Don't let anything like Winrar mess with it. Don't try to look inside.
Volume down while powering on, get to FASTBOOT USB mode while plugged in to PC.
In command window say -
fastboot flash recovery twrp-2.8.7.0-m8.img
Get a working rom to flash (install).
I recommend ViperOneM8.
If (and only if) you were already running Lollipop, get version 4.5.0.
If you were on KitKat, get 2.3.1.
http://venomroms.com/htc-one-m8/
On your phone, go to HBOOT and from there into RECOVERY.
TWRP launches.
TWRP, Mount - mount the internal storage or sd card by checking the box.
Your pc ought to see your phone at that point, copy the ViperOneM8 zip file to the phone.
Uncheck ONLY the storage you checked on to make it work when done.
TWRP, Install - choose the ViperOneM8 zip file.
The ViperOneM8 installer launches.
When prompted choose -
- Full wipe
- Install full stock rom
- Do NOT remove optional apps at this point
When done, set up phone per normal.
When complete, long press power for menu, reboot, choose recovery from new menu - phone boots directly to TWRP.
Choose Backup - accept defaults to make a full (nandroid) backup.
Your phone will be properly rooted when complete.
