[One (M8s) General] daveog3:
My thanks to mobilescooby, followed the instructions and finally got the phone updated to Marshmallow follow the OTA failing to install with a Status 7 error. A couple of things had me holding my breath though with your instructions. I assume that update one once complete leaves the phone with no OS ? as it would only boot to the HTC One startup screen. Got back into hboot by holding the up/power button to get the phone to reboot and then the down/power button to get it in the hboot menu as it was rebooting.

Once back in the hboot menu I wasn't sure how to get the second file on to the sd card as i couldn't see the phone storage on the pc and wasn't sure if the sd card was mounted at this stage. Finally took a chance and just took out the sd card and transferred the second file on to it and went to fastboot then hboot. First attempt failed because I hadn't checked the second file, its zipped twice so extracted and renamed the internal zip and transferred that to the sd card. Finally success, install started, took about 25 mins, seems to be on the system update forever between installing and updating multiple times.

Based on my experience i'd modify the instructions slightly

1. First put file 1 on your SD card make sure the filename is 0PKVIMG.zip and reboot to HBOOT (bootloader)

2. Let the file be detected and it will give you the option to flash it, updating the recovery to stock and it will reboot.

3. Go back into FASTBOOT and issue FASTBOOT OEM LOCK from you computer. (This will relock the bootloader) -> (Not necessary if you have a stock phone , not unlocked, like me)

4. Your device will probably bootloop at this stage! it did me. ->(Same here black screen, almost heart failure thinking I bricked it)

4.5: Remove sd card as going into hboot will start the update of file 1 process again, and put into pc. Phone doesn't seem to be able to be turned of at this stage so I formated the sd card again in case removing it while the phone was on caused it to get corrupted

5. If you have ADB access, simply issue adb reboot bootloader to get back to HBOOT. or simply use the vol down and power button combo to get back into the bootloader.

6. Check the HBOOT screen and you should now notice that it should say something like OS-2.10.401.1 and ***RELOCKED*** at the top. ->(or OS-2.10.401.1 and ***LOCKED*** if doing this on a stock phone)

6.5. Open file 2 on your pc and extract the zip file inside. Rename the extracted file to 0PKVIMG.zip and place it on your sd card overwriting the other one. Insert sd card into phone

7. Go back into HBOOT (bootloader) -> (switch between hboot fastboot hboot)

8. As before the phone should say it found an image and offer to flash the file..... This is where you cross your fingers and go make a coffee or something. The process took me about 10-15 minutes to flash. -> (Closer to 25 mins for it to flash for me. System takes forever switching between installing and updating multiple times. You will see a vertical bar on the top right side of screen showing it updating )

9. Simply follow the onscreen options and hopefully you'll get asked to press power to restart. Give the phone a few minutes to do its thing then all being well you'll be back in stock MM. ***Happy Days***

Again thanks for all the help here, my providers help consisted of telling me to contact HTC