Thank you all for your help. Problem is that I am from India where there are no official dealers for any quality home theater products . You have to trust the dealer. I think the sub is new. I wrote to SVS people and like you all said they were very prompt in replying. This is what they have to say-
"Since the sub has a light we are not sure if the problem is the amp or the driver (both of which are user-replaceable if required, no need to ship the entire sub) or possibly just a loose connection. So please remove the amplifier per the attached instructions.
Once the amp is removed, please check the spade terminals at the driver for a tight connection - it's possible one of the spade terminals became loose and disconnected from the driver. If a spade did become disconnected, please gently crimp down the female section to create a slightly tighter fit and reconnect and then test for proper subwoofer operation.
If the spade terminals are tightly connected, please check the woofer next. Please touch a 9V battery to the pin connections inside one of the white plastic connectors attached to the woofer wires you disconnected from the amp. Use a pair of unfolded paper clips to reach the pin connections inside the white plastic connector per the below photos (the photos show red/black wires but your wires are brown/blue). When the battery voltage is applied to the white plastic connector, the woofer should then make a burping sound and move about 1/4" in one direction. This will mean the woofer is OK, and will then confirm it's a defective amp."
Hopefully it works. Thanks again to all of you. With love from India.