These are the things That I have successfully tried on HTC M8 phone in attempt to install update on the phone.These things may or may not work on your phone.I can't responsible for the results you come up with.Use at your own risk.
My Phone - HTC M8 T mobile(US) , S-OFF ,Unlocked Bootloader ,Not rooted,Super CID and TWRP Custom Recovery Installed .
PC - Windows 7 (64) , latest [HTC sync Manager] and Fastboot &Adb tools Installed.
How to Factory Reset Using TWRP recovery HTC M8
1. First you need to setup TWRP recovery in your HTC M8 .[Here is How To]
2. Go to bootloader mode and select Recovery .
3 In TWRP recovery mode select Wipe .
 |
| Factory Reset Using TWRP |
 |
| Factory Reset Using TWRP |
4. Swipe to factory reset.
5. Then you will see something like this .
 |
| Factory Reset Using TWRP |
6.Select back .you will return to the TWRP main menu then select Reboot.
Rerutn to - [HTC M8 Tutorial Collection]
