[One (M9) Q&A, Help & Troubleshooting] Nikolay82:
Getting the 2.10.401.1 step by step, crystal clean instructions.

This guide is mostly for the people who are stuck on lower versions where "About" says that there are no updates and that their device is up to date. Especially users who previously did 1.32.401.17 RUU. This version is know to have some major flaws and it tends not to read any updates, accept auto and manual OTAs nor zipped RUUs.

- Alright so I saw good number of people being stuck on European 1.32.401.17, 1.32.401.15 and 1.32.401.8 and unable to grab auto OTA and unable to manual OTA install due to various errors being thrown in twrp. There are also users who are having issues with SD transfers, transfers from PC to to phone especially when they transfer zipped RUU (0PJAIMG). Do not worry, I am going to help you with this. Just follow my simple steps. Note that you can forget about custom recoveries, microsds, system dumps, zipped ruus that "wont copy" to your device and others. You won't need any of these in my procedure. Simply ignore them. Now focus on my steps.

Step 1; Download the 1.32.401.17 exe RUU from here; DO NOT RUN THIS YET.

Step 2; Download the 1.40.401.8 0PJAIMG (ZIPPED RUU). Do not open/modify this yet.

Step 3; Backup your data on the phone such as contacts, SMS and so on. I personally use Wondershare mobilego for those things.

Step 4; Navigate to temp folder by typing %temp% in the search bar or C:\Users\Username\AppData\Local\Temp\ >>

Step 5; Under that folder you may or may not delete the files you don't need for easier navigation. Now this part is very important. Focus on that folder.

Step 6; Go back to 1.32.401.17 exe you downloaded in the step 1. Right click on it and Run it as admin. Once ran, it might take several minutes to open actual installer. Let it load all they where you see next/cancel. Stay there and do not cancel it or hit next.

Step 7; Go in your temp folder under step 4. You will see two newly created folders. You only need this one. Under that folder you should see another one with few random files. Go into other subfolder and navigate to the file named rom.zip. Delete this folder.

Step 8; Now go back to the file you downloded in step 2. Name that file to rom.zip and place it where you previously deleted the zip file from temp subfolder.

Step 9; Go back to the RUU installer interface and press next and do the procedure like you did with version x.17. You should see this. Now let the RUU installer updates your phone.

Step 10; Go under Settings > About > Updates. Now if you did all right you should see the magic: http://i.imgur.com/aqR4YwD.png >> Grab this new 100% fresh and stock OTA update and enjoy.

- I tested this few times on several devices and it works for every one of them. I am not aware of the other carrier users are having issues but same procedure can be done. Do not install custom recovery or root your device before you updated your device to 2.10. If in any case updater wont pick the 2.10 update you can flash your recovery and firmware from 1.40.401.8 version (prior to the 2.10 update). Do not panic if update is taking a while, it will reboot your device few times and thats it. To be on more safe side you can always flash the firmware once device is properly updated to 2.10.

*Flashing the firmware to 2.10*

Download from here and put it where your ADB interface is;

Put your device to download mode and open up the cmd where adb interface and latest firmware is.

do the following commands:

a.) fastboot oem rebootRUU

b.) fastboot flash zip firmware.zip

c.) fastboot reboot

- Make sure the phone is not rooted or tampered with. If something is not clear feel free to ask. I hope this helped to you.

Nikola