How To Unbrick HTC One M8 Eye !

The steps are same for flashing 

Step 1 - Download and extract TWRP folder on your computer.

Step 2 - Copy TWRP folder into external sdcard (size - 1.4 gb approx).

Step 3 - Power off your phone and insert the sdcard into phone.

Step 4 - Boot into the bootloader by Power key and volume key down (-) , Then select 'Recovery'.

Step 5 - In TWRP recovery select restore and above you will see an option to select internal sotrage/external sdcard, select external sdcard.

Step 6 - A backup will appear, select that and tick mark only system.

Step 7 - When restore is complete reboot the phone.