Up, up, down, down, left, right, left, right, B, A...no, you did not unlock Xbox One backwards compatibility.
Microsoft has made it clear that the Xbox One is not backwards compatible (at this time, although the company did say it's looking into cloud based gaming). That means no matter what you do - check a box in dev mode, cover your console in four-leaf clovers, clutch a rabbit's foot and pray for Halo 3 - it won't work.
If you tried any of these and still do not believe me, Microsoft's own Major Nelson has confirmed that Xbox One consoles aren't backwards compatible in a tweet. If you see any kind of method for enabling Xbox One backwards compatibility going around, don't believe it - at best it's a harmless prank, at worst a malicious scam.
