have a gift card from i-tunes bad card code error

I got a question

have an i-tunes gift card with a bad code number.

cant redeem it, or possibly been used I can't remember ??.

and have an apple tv black box w/remote, I've

got another uverse box about a month ago, how do I hook it up

to the new equipment.

and i'm not sure if the apple tv unit is about a year old give or take

have a great day