how to downgrade hboot of htc desire hd?

info:

Code:

---

version: 0.5
 version-bootloader: 2.00.0030
 version-baseband: 26.16.04.09_M
 version-cpld: None
 version-microp: 0438
 version-main: 3.17.1010.1
 serialno: HT11TTH00604
 imei: 355778041131915
 product: ace
 platform: HBOOT-7230
 modelid: PD9815000
 cidnum: KT___901
 battery-status: good
 battery-voltage: 4126mV
 partition-layout: Generic
 security: on
 build-mode: SHIP
 boot-mode: FASTBOOT
 commitno-bootloader: 62d2f26e
 hbootpreupdate: 11
 gencheckpt: 0
 region-id: 0

---

1st of all i want to unlock bootloader, i tried, all thing done successful but after restart still locked.
can anybody help me to unlock it's bootloader?

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