one m8 ul can not select unlock bootloader-is it flash ic problem?

set hang in logo then off-details as below

C:\android>fastboot getvar all
(bootloader) version: 0.5
(bootloader) version-bootloader:
(bootloader) version-baseband: 1.29.214500021.12G
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main: 6.15.720.2
(bootloader) version-misc: PVT SHIP S-ON
(bootloader) serialno: HT46EWM02154
(bootloader) imei: 352442060319918
(bootloader) imei2: Not Support
(bootloader) meid: 00000000000000
(bootloader) product: m8_ul
(bootloader) platform: hTCBmsm8974
(bootloader) modelid: 0P6B65000
(bootloader) cidnum: HTC__038
(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: 205bdca3
(bootloader) hbootpreupdate: 11
(bootloader) gencheckpt: 0
all: Done!
Execution time is 15(ms)

did not get this version """6.15.720.2""" file-so i think about custom firmware and did bootloader unlock.

now phone screen bootloader unlock?
but can not select ""yes""automatic come to ""no"" when select yes is the problem-i think it emmc problem

am i right?