Lock 4G vivo y series y91c, vivo y15, y95, v7, v9, v5s, y71, v3, y51

Engineer Mode *#*#3646633#*#*

You can follow these steps to call up Developer options:

1. Enter Settings,More settingsAbout phone(Version)

2. Click seven times at Software version

3. Developer options will appear in Settings,More settings.