[One (M8) Q&A, Help & Troubleshooting] redpoint73:
This is actually not that stupid of a question. The thread lists stock nandroid, OTAs and RUUs.

The method you want, is to restore the stock nandroid that corresponds to your CID and current firmware, then stock recovery. The process is explained a little further in Post #3 of the thread: http://xdaforums.com/showthread.php?t=2701376

---------- Post added at 10:07 AM ---------- Previous post was at 09:43 AM ----------

You can find any 4.4.3 based stock or custom ROM, and WiFi will work again, as I've already stated.

If you want to return to stock to OTA and update your firmware (and run current ROMs) the basic premise is rather simple: Restore to stock ROM and stock recovery, allow the phone to update by OTA in order to update the firmware. But some of the individual steps can be tricky. You need to:

1) As mentioned above, find the stock nandroid for your CID, which is under "All other CIDs" on the stock nandroid thread. Scroll down to find HTC__622. The one labelled 2.11.708.2 is the one you want, as it corresponds to your present hboot, radio number (4.4.3 firmware). Download that stock nandroid.

2) Unzip the downloaded nandroid folder. Place it in the proper location as indicated in the 2nd question under "Questions and Answers": http://xdaforums.com/showpost.php?p=58128936&postcount=3

This part is very important, since if the files are not placed in the

exact

correct location, TWRP won't see it.

3) Boot into TWRP, select the "Restore" function, browse to the stock nandroid, and restore it. You are now restored to the stock ROM.

3a) Alternately, if you were smart enough to make a TWRP backup of your stock ROM before you flashed any ROM (and you

really

should have), you can just skip all the above steps 1-3, and restore your stock nandroid. Root is okay, just as long as you didn't modify any /system files after root.

4) Download stock recovery that corresponds to 2.11.708.2 from here: https://www.androidfilehost.com/?w=files&flid=24391

This is linked in the stock nandroid thread, but I thought I'd be nice and just give you the direct link, since I've already got the page open.

5) Use fastboot (with phone connected to computer) to flash the stock recovery with command: fastboot flash recovery filename.img

Where "filename.img" is the actual name of the stock recovery you downloaded.

6) Now you are on stock ROM

and

stock recovery. Boot the phone, and in Settings check for an OTA update. Run the updates. You will probably have 2 OTAs, one to get you to 4.4.4, then another to bring you to 5.0.

7) Once the 5.0 Lollipop OTA is installed, it also means your firmware is current (LP firmware) and you can run LP based custom ROMs without having WiFi issues. To do so, you first need to:

8) Install TWRP again.

9) Flash whatever LP ROM you want.

---------- Post added at 10:21 AM ---------- Previous post was at 10:07 AM ----------

2.23 isn't the radio number, its the software number, and is the one for the old Android 4.4.3 update. This would actually

revert

you to radio 1.18 or 1.19 or somewhere thereabouts.

The latest radios (Lollipop) are numbered 1.2x. So you are on a current LP radio. The only AT&T specific Lollipop radio at this time is the Developer Edition, which is 1.24.21331147A1.09G_20.68.4196.01_F

We won't have a "real" AT&T Lollipop radio, until they roll out the LP update.