[One (M9) General] Tetragrammazoid:
I had an accident and, I also have Tinnitus and PTSD, so concentration and memory took a knock. Understanding isn't what it used to be for me, so, I'm sorry if I come across as just someone that can't be bothered reading.

I just needed a bit of extra help, however that's absolutely fine if people are busy etc. I can get that. Life is quite short, I live opposite Grenfell Tower and am reminded everyday just how short it is.

Anyway, I read and reread and reread and read, I contacted a few people too such as the Sunshine S Off people for advice. It's fixed now!

I found some files here on the "read me" thread too which were very useful. Thanks to the uploaders and maintenance people, thanks Flippy!

If anyone is reading this and has the same problem as me, with the same phone software, here is what I did:

Anyway in the end I used a "combined_signed zip" which had been extracted from the RUU for this particular phone and software by someone

(*****the CID and MID matched which is very important. This is the file I used which matched my phone *EXACTLY******):

https://androidfilehost.com/?fid=817550096634776616

The "combined_signed zip" can only be used with S-On if it matches ***exactly including CID & MID***. It can be flashed with the S-On (security) if it *matches exactly* – that's what I did). I can't emphasize that enough, otherwise you might break your phone!!!

I downloaded the zip file named above to my computer, the instructions I had read said to rename the file,

"0PJAIMG_HIMA_UHL_N70_SENSE80_MR_Vodafone_UK_4.17.161.11_Radio_01.01_U114401031_124.01.70203G_F_release_500907_combined_signed_2_4"

to,

"0PJAIMG.zip". I wasn't sure if the 0 at the front was a zero or an o, so I just deleted the everything after the "G" instead of renaming by typing.

Next, I put the file on the root of a *fat32* SD card (the "root" means the area you get to when you click on the SD card *NOT A A FOLDER INSIDE IT*).

The storage requirements of the SD card: (not more than 32GB storage was advised for other phones but the HTC One M9 is reported to be ok up to 128 GB. However, I used a 32GB one from my MOTO G2 that was already formatted to *fat32*.

(It should have at least 8GB free space!).

I put the SD card in the HTC One M9, turned the phone completely off, waited 15 seconds. Then I booted to "Download mode" (power button and volume down button held down) and it detected the zip, asked me if I wanted to flash it atbottom of screen. I confirmed (with the power button). It started saying "updating GUI" then seemed to stop, I pressed the power button two more times in total. It loaded and updated all the files in the zip after 5 minutes or so. It confirmed it was done and I selected reboot by confirming the on screen option. It rebooted and loaded the new system. Everything is working.

Root was lost, as was TWRP too. I double checked TWRP was gone by booting to recovery where a phone screen and a red triangle was shown. It seemed to be stuck on that screen with no other option and the phone wouldn't turn off when I held the power key which nearly gave me a metaphorical heart attack. I pressed the power button a few more times then just left it, it eventually rebooted which was a relief but I hear you can press volume UP and hold the power key to get to a HTC recovery menu from that triangle.

I found this file, it appears to be a STOCK GSM backup (Not the Vodafone VODAP100 as was on my phone when it came originally, so MID probably doesn't match) if used it ***would need S OFF*** as the MID or CID won't be a match. I'll leave the link here just in case anyone wants to flash it:

https://androidfilehost.com/?fid=673368273298938357

I could try making a backup of my current software with TWRP if I root my phone again too. I will have to see if I install TWRP again.

Anyway, so, that's it. It's fixed now. I'd still like to root but since all this, I've read that Google Pay and NFC doesn't work with rooted phones because Google considers a rooted phone to be unsecure. I've also read that another method for rooting exists, called "Magisk" and apparently Google Pay and NFC work with it, BUT it looks like there have been quite a few problems with it too from what I've read.

If anyone has any tips about Magisk or other methods that'd be great!

Thanks. Tetragrammazoid out.