The full SBF for ATT 4.4.2 hasn't leaked yet. When it does it will be put up on ->
http://sbf.droid-developers.org/phone.php?device=0
Until then, an alternate way to reboot the phone in bootloader/fastboot mode, and issue the following commands...
mfastboot erase cache
mfastboot erase data
mfastboot reboot
If you are struggling to get into bootloader/fastboot mode... with your phone booted normally, usb debugging enabled, and ADB and its drivers properly installed and added to your PC's path... connect the phone to the PC via USB cable, open a command prompt and issue the following...
adb reboot bootloader
However, the OTA will only install if you have a stock recovery on your phone. The message about "Partition (recovery) security version downgraded" tells me you may have the Stock Recovery from 4.4 or 4.2.2 on your phone, rather than 4.4.2.
Since the ATT 4.4.2 SBF isn't out yet, try downloading the Verizon or T-Mobile 4.4.2 rom from ->
http://sbf.droid-developers.org/phone.php?device=0 unzip it... and use fastboot to flash that recovery.img to your phone..
fastboot flash recovery recovery.img
---------- Post added at 06:18 AM ---------- Previous post was at 06:14 AM ----------
Correct. If you have a locked bootloader, and took the 4.4.2 update, you might retain root. but you lose the "Write Protection Disable" that MotoWpNoMo gave you.
On 4.4.2, there is no way to disable write protection unless you can unlock your bootloader. If you lose root, on 4.4.2 there is no way to root.
If you flash the 4.4.2 SBF you wont be able to root and disable write protection if you can't unlock your bootloader. And don't try to downgrade to 4.4 or lower.
If you have ATT, the Chinese web site was the only option to unlock your bootloader, however that seems to have ended.