[Q] Phone stuck on bootloader after relocking bootloader

After relocking the bootloader, my phone is doesn't boot to system it just shows the htc logo and goes straight into bootloader.
Here is the info that it shows:
***Software status: Modified***
*** RELOCKED***
***Security Warning ***
M8_UL_CA PVT SHIP S-ON
HBOOT-3.19.0.000
RADIO-1.24.21331147A1.09G
OpenDSP-v62.2.2-00593-M8974_HM.1118
OS-4.16.1540.8

HBOOT
RAMDUMP
REBOOT
REBOOT FASTBOOT
POWER DOWN

I saw it on this thread that I can download an run RUU to fix this, and I've download this file for my AT&T M8. My question is, will it be all right to run this? I'm just making sure as I don't wanna brick my device. And if this not the way to go, can anyone help me in any way? Any help would be great.

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