[Q] Unable to update lollipop via OTA topic

hi guys
i just got a new Galaxy S4 with 4.4.2 version out of the box. as i can see Lollipop is available in india but i am unable to update via OTA.It shows "Latest Updates have already been installed".
Please tell me can i update from firmware file of sammobile without voiding the warranty.

Please guide me
thanks