Just one question first. Does your amp even turn on at all? check your amp light if it activates when you turn on the radio.
If it doesn't then check your remote line going into your amp if you are getting any power there.
But regardless of the amplifier, it sounds as if your radio is shot. Circuit sold you a bum deck.
Go back there and they should be able to look at the installation. but since you're passed their 30 days return policy you probably have to get a new radio or send that one out to JVC to get their warrenty