I have tried the SN, the ICC ID, and IMEI, and reconfirmed the numbers are correct. It won't accept any of those, so which number does it want when asking for the Serial Number?
meaning, once it is redeemed and in your account, does it expire?
because if you read the terms for when they had the nexus 7 credit last year, it states 4. Redeemed balances that remain unused in your Google Play account will expire on September 30, 2013 at Google Play Promotional Balance Terms