[Issue] Unlocking bootloader HTC Desire 816

Hi All,

I am trying to unlock bootloader in htc desire 816, as i read from blogs i got a Unlock_code.bin file from HTC then i tried "fastboot flash unlocktoken Unlock_code.bin" after this it's gives a pop up in my htc phone with YES and ON option i select YES then phone goes to recovery mode and i received the following error :-
E: missing bitmap oem_unlock_bg
(Code-1)
E: missing bitmap oem_unlock_bg_yes
(Code-1)
E: missing bitmap oem_unlock_bg_no
(Code-1)
Write host_mode success
handle_cota_install: Can't mount /sdcard, 1 times
handle_cota_install: Can't mount /sdcard, 2 times
handle_cota_install: Can't mount /sdcard, 3 times
handle_cota_install: Can't mount /sdcard, 4 times
handle_cota_install: Can't mount /sdcard, 5 times

and i can see as "LOCKED" in the bootloader.
The issue is my HTC 816 keeping on rebooting automatically every 30 seconds( Don't know why) so trying to put custom ROM so that may be this issue can be resolved.

Please do HELP!

Thanks in advance.