I flashed few times and i got problem for two reasons:
1) i forgot to wipe properly (I suggest to: fastboot -w, fastboot erase system, fastboot erase data, fastboot erase preinstall, fastboot erase cache)
2) I forgot to remove sd-card (f_k*d off) and sim-card (this had more luck)
Flash with battery fully charged and I think you'll enjoy.
- Fastboot wipe (optional)
- Remove sd card and sim card (necessary)
- Make sure you have proper drivers (necessary)
- Use the latest RSD (recommended)
- Make sure you have the correct (signed) SBF, best to use the build that the phone was last on officially (important)
- Double check everything (important)
- Put the phone into RSD mode (then plug it into the computer) and select the appropriate file in RSD and press "Start" (cross fingers)
Always use caution when using RSD. If you're not sure about something then find the answer FIRST.
Disclaimer: I am not responsible for any damage you might cause to your phone by following these instructions. This is a suggested overview and you should put in the proper amount of research and time to make sure you are doing things correctly.
With that said, depending on why you want to return to stock it may be preferable to use a "Fruitcake" as others have suggested, but I have successfully used RSD Lite to return my phone to stock in the past so it is "possible", though not recommended.