HTC One M7 Bootloop; Can´t unlock Bootloader

Hello everyone,
i hope this is the right section for my question.

Two days ago i bought a used HTC One M7 which was stuck in a bootloop with the hope to repair it.
It boots to the homescreen with the bar on top and a black background and then it reboots.

Now i wanted to unlock the bootloader and flash a custom recovery but the thing is, i cant unlock it. After completing the steps on htcdev it reboots and when i return to the bootloader it still says "locked"

Here are informations of the phone:
version: 0.5
version-bootloader: 1.54.0000
version-baseband: 4A.17.3250.14
version-cpld: None
version-microp: None
version-main: 2.24.401.1
version-misc: PVT SHIP S-ON
meid: 00000000000000
product: m7_ul
platform: HBOOT-8064
modelid: PN0710000
cidnum: HTC__102
battery-status: good
battery-voltage: 4312mV
partition-layout: Generic
security: on
build-mode: SHIP
boot-mode: FASTBOOT
commitno-bootloader: dirty-d16dc66985
hbootpreupdate: 11
gencheckpt: 0


the meid looks suspicious to me, is it normal?
Ok i just learned the meid is normal for GSM models, but the problem with the bootloader persists.

I hope someone can help me.