You can only flash the OTA file that corresponds to the firmware that you're currently on. So if you're on 4.3 (ML2) then you have to flash the ML2->NE3 OTA file. If you're on 4.4.2 (NC9) then you have to flash the NC9->NE3 OTA file. If you're already on NE3, messed something up, and want to flash stock NE3, then I think you have to start over and go back to ML2 but I could be wrong. Somebody please correct me if I am.
Safestrap remains, always there on boot up after a shutdown. Wish Safestrap to be fixed for loading flashable Slot-1, Slot-2 etc. in NE3 4.4.2. Tried but Slots still do not work, but the flashable backup still does.
@Devo7v , it would be quite a developer accomplishment to create a flashable update.zip similar to the renamed OTA cfg file, that still has the locked BL, but have built in user customizations. Such a basic update.zip could already have a a pre-configured root via towelroot.com.
Anyway just wanted to mention I did somewhat get my 'almost' stock NE3 reinstalled the Safestrap TWRP way.