Yeah, that's not the way to do it right. I don't honestly know why they all keep putting out apps, but that's them, and I'm me.
You're going to download a few things and run one command.
First, get the Mini-SDK, it's a download called sdk-tools.zip - get it, unzip it.
http://androidforums.com/threads/adb-guide-updated-2014-11-11.443072/#post-5389081
Get this TWRP, it's good for all M8 variations -
You want TWRP_Recovery_2.8.5.2_M8_CPTB.img
https://basketbuild.com/devs/Captain_Throwback/One (M8)/ALL/Recovery
Copy or move the downloaded file into your sdk-tools folder.
Turn off your phone. Hold volume down while powering up. A white screen with colorful text appears.
Plug the phone into your PC - the words FASTBOOT USB will appear in highlighted letters.
Go to Windows Explorer. Single click on sdk-tools folder. Then shift+right click to get a menu.
Find - Open command window here (or words to that effect, depending on your Windows).
In the command window say -
fastboot flash recovery TWRP_Recovery_2.8.5.2_M8_CPTB.img
Pro tip - you can copy that command from here and paste into the command window.
Select the command here with mouse, and copy.
Click on or inside the command window. Then Alt+shift will bring up a menu, press E for Edit, P for Paste. Hit return.
You'll see some bytes transferred, upwards of 16k (I forget the exact the number) - and finally OKAY.
Reboot your phone -
Hold volume down key while powering on - select the HBOOT option, and from that screen, the Recovery option.
You'll see the main TWRP menu.
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STOP AT ANY POINT IT DOES NOT BEHAVE AS I SAY AND POST BACK.
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Your rom is corrupted. TWRP can't fix that. You can do a backup in TWRP of it in TWRP anyway - why not?
Go ahead and do that.
Then, reboot your phone.
You need a working rom.
I recommend ViperOneM8 - it's stock on steroids, and built-in help with Xposed.
http://venomroms.com/htc-one-m8/
Navigate to downloads, previous roms, for KitKat look for the place that says
Latest Fullrom: ViperOneM8 3.2.1
Get that from PC. Plug running phone into PC - copy the rom to your storage, not inside a folder - so you can find it easily - and either internal storage or sd card is fine.
Pro tip - you can stop now and install Titanium Backup and backup your stuff if you haven't already. If new and you don't have Busybox, follow the on-screen prompts.
Go back into TWRP using volume down power trick.
Select Install - navigate, choose the Viper Rom.
A wizard installer launches. Choose to let it wipe for you.
DO NOT choose anything else fancy right now - just choose your carrier and choose to install Viper.
After you're up and running, you can choose the Venom Tweaks app, and you'll find a tab for the Xposed.
If you made a Titanium Backup, restore it now.
Once you have everything up and running, hold down the power button like you're going to turn off your phone.
A menu appears. Choose Reboot. From there, choose Recovery.
You're now in TWRP - make a nandroid backup (default if you choose Backup from the main TWRP menu.
Reboot when done.
Enjoy your repaired phone.
