Device not booting and not allowed me to unlock boot loader

Everytime I try to boot the device HTC Desire 728 I am getting a white screen with *** Software status: Modified *** *** Locked *** HTC_AS0CML 128 SHIP S-ON *** Security Warning *** CID-HTC__J15 LK-1.01.0000 OS-1.36.401.4 VOL Up to previous item VOL Down to next item Power Key to select item REBOOT REBOOT TO BOOT-LOADER BOOT TO DOWNLOAD MODE BOOT TO RECOVERY MODE POWER DOWN Tried Booting into recovery and selecting "wipe data and factory reset" but still the same problem. Tried to fastboot boot .. but it says FAILED (remote: 'download for partition 'unlocktoken' is not allowed') fastboot: error: Command failed I searched the web and found that I must first unlock bootloader (see this link ) **But however my device is locked and I cannot even boot it to enable "Developer Mode" and "Enable OEM Unlock" options from settings.** Can you suggest what to do?