Boot loop after flashing stock rom and update (HTC One M7), how can I fix it?

[AC Question]

Boot loop after flashing stock rom and update (HTC One M7)

Hi all,

Hope you can help please.

I have been using a custom rom for a while and decided to flash back to stock rom, I used an RUU file which matched my CID etc, the phone rebooted and was working great, I then installed the OTA update and after the phone is in a constant boot loop, I flashed another RUU which also matched my CID etc but same result, also same result with GURU reset files.

Can anyone help with the above please, have I missed something?

Thank you,
Dean.