If you need to flash a new ROM onto the device first unlock it's bootloader,
then flash a custom recovery (the twrp 22.214.171.124 given in one of the threads)
then proceed with whatever you wish to do.
I also used it, and it resulted the same that my htc desire 526g+ got stuck in a boot loop. In my case, it even got stuck in a bootloop in recovery mode. Now I had to give it for repair at the service center.
So, I would suggest you to proceed with serious caution.