How to update to HTC One M9 Lollipop or Marshmallow?

Hi everyone,

I need some help if you may please. I bought an HTC One M9 phone and for a while it's been telling me to update to the newest android version. However, this was impossible because even when I downloaded the update from TMobile, when restarting, TWRP would kick in and wouldn't let me go through the whole setup. So, I got to some tutorials and I found some guidance but it's all so confusing and I've gotten to a point where I have no idea what to do next.

Phone is from:
-TMobile


What I did:
-Got rid of TWRP
-Got it back to unroot

Phone status as of now:
It works fine, but it's still not updated.

When going into the HTC Download mode screen, i get the following info:
-UNLOCKED
-htc_himaul PVT S-ON
-OS-1.32.531.24
-Warning: Security checking failed NOT_FIND_SMARTIO
FILE /mnt/media_rw/ext_sd/0PJAIMG.zip
File NOT FOUND

ADB is not reading my device when in download mode, I was trying to install stock recovery by following a tutorial in android soul: how to install stock recovery on htc one m9 (sorry but the forum won't let me post the link)

What do I need to do? There are so many tutorials out ther with so many different instructions that I'm totally confused now as to what to install or not to install . I'd like to install the Developer version but if I have to deal with the Tmobile one, that's ok.

Thanks in advance!

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