The backlit keyboard is optional on this model. When you start the system, if it has a backlit keyboard, you'll see it illuminate briefly.  If it does not, you have a standard non-backlit keyboard. If the system is brand new and you need that option, your best course of action is to exchange the system.  To replace a keyboard on this model requires a palmrest assembly replacement, which in turn means the entire system must be torn apart.Service manual shows the details. [URL]  
Can anyone help me find out keyboard backlight for my vostro 15 3510 laptop. I face too much difficulty using the laptop at nights. Is the model have inbuilt backlight or not?
Dell vostro 15 3510 keyboard backlight