We are aware that a lot of people are having issues with redeeming your code for the Black Ops 3 beta.
We have received word that there was a work around that you can use. After testing it we can confirm that this does in fact work, so here is how you can redeem your beta code so you can start the download on your console.
Go to your internet browser and enter this link: http://www.xbox.com/redeemcode
At the base of the page you have the option to change the language, select Brazil.
If you are comfortable navigating around the Brazil Xbox site you can use this link and go directly there: https://account.xbox.com/pt-BR/PaymentAndBilling/RedeemCode
Enter your beta code and click on the button that would normally read confirm.
Your code has now been redeemed and you will be able to find the beta for download on the Xbox One dashboard.