Read this thread carefully, it has info about not mounting issues !
http://xdaforums.com/showthread.php?t=2850470
Maybe this applies to you too
Ok now I am able to do the fastboot getvar all cmd, here it is:
(bootloader) version: 0.5
(bootloader) version-bootloader: 3.16.0.0000
(bootloader) version-baseband: 1.16.2133156.UA15_2G
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main:
(bootloader) version-misc: PVT SHIP S-ON
(bootloader) serialno: ---
(bootloader) imei: ---
(bootloader) imei2: Not Support
(bootloader) meid: 00000000000000
(bootloader) product: m8_ul
(bootloader) platform: hTCBmsm8974
(bootloader) modelid: 0P6B11000
(bootloader) cidnum: VODAP021
(bootloader) battery-status: good
(bootloader) battery-voltage: 0mV
(bootloader) partition-layout: Generic
(bootloader) security: on
(bootloader) build-mode: SHIP
(bootloader) boot-mode: FASTBOOT
(bootloader) commitno-bootloader: ab0efa49
(bootloader) hbootpreupdate: 11
(bootloader) gencheckpt: 0
all: Done!
finished. total time: 0.204s
Hope this helps
Also I have tried to fix using the solution mentioned though I don't know where to download the "mkfs.ext4 binary".