Xbox – Will replacing stock fan ban the console

Opening your Xbox 360 is not the same thing as modding it.

Modding, short for modification, refers to the act of making changes to your system in order to favorably (and often illegally) circumvent a blocking mechanism. For example, you might mod your Xbox 360 so that it can play burned or downloaded games without permission. This will get you banned from Xbox Live and disowned by Microsoft.

Opening the system, on the other hand, will only void the warranty. It's not illegal and you won't be penalized for it, especially since your warranty has already expired. However, Microsoft may refuse to officially repair your system, in the event that your friend is unable to revive it.

Edit: There's no way Microsoft can detect from afar if you've opened your box and fixed it yourself. They don't want you doing your own repairs because a) you might turn around and blame them after you've made things worse, and b) because they make money from doing the repairs exclusively.

Although it does violate the Xbox Live terms of use, you can't be detected and locked out unless you explicitly tell Microsoft that you opened the box and fixed it yourself.

Short Answer: Your console will not be recognized as modded.

Yes, you can login to the Xbox Marketplace and redeem the code there. Click the "Redeem Code" link under "My Account."