In RETAIL DEMO the phone start demo video and do this every time it goes to sleep mode. Older version of Android have a bug, that allowed to change the screen lock if the phone has Lock screen. For the newer version you can't enter "Retail mode" if the phone is screen locked.

To enter and go out this mode, from the Dealer app enter this code:

*#*#73556673#*#*

That's all.

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Did you do it successfully.