can I enable android on my device which is of Samsung Rex s3802? I am trying to enable this on my device for an hour but nothing's working!
Very unlikely. The Samsung Rex 70 S3802 is a feature-phone with just 10 MB internal storage (even Android versions before 4.x required more than 200 MB just for the system stuff).

For reference, the same question was asked back in 2013 when this phone debuted: Can I make a Samsung Rex 70 an Android phone? – where all answerers came to the same result. I also very much doubt someone has written a ROM for it (hard to do due to the mass of proprietary hardware elements of the device, including its CPU), provided this background – so no ROM, no install.