HTC M8 Stock firmware update red triangle

A

AC Question

Hi there,

I'm trying to fix my HTC One m8 phone. I tried updating it to the latest software update and I am now stuck on an infinite loop with a red triangle and exclamation mark.

I've never done anything to the phone (it's completely stock as far as I'm aware) and I've only ever updated via the settings menu.

I'm really not sure what to do from here.. I'm completely confused as I've never rooted a phone but it's now useless. How can I get it to work again? From the internet I've worked out how to get to the menu.. which gives me the following options:

Reboot system now
Reboot to bootloader
Apply update from ADB
Apply update from SD card
Wipe data / factory reset (I tried this option.. didn't help)
Wipe cache partition
Power off

it also says:

handle_cota_install: No CW files.(There is other text but it goes off screen)

When I went into bootloader it says "software status: official then ***LOCKED***"

Does anyone have any idea on what to do?

Many thanks for the help!