Is this gamer tag mod possible

I saw something on YouTube where you can change your Xbox live gamer tag with le flufee so I open my Xbox profile on le flufee and when you click on edit profile it says edit gamertag so I changed the gamertag to logic and saved it rehashed and resigned it on modio and put it in my USB and I went on my profile name and it said logic but when I click to sign in it says error I need help

I don't have a solution to your answer but if I was to take a guess I would say that it's for multiple reasons.

Firstly being that the online profile Logic is already taken.
Secondly, you're using third party applications to mod your profile.
Thirdly, these third party apps. do not have the power to change the attributes of an online profile such as "Gamertags".

I'm not sure if these are correct but it's a guess.

This was patched a long time ago. It was mainly used for CoD and you'd try to click multiplayer it'd say no, then you'd choose your real account and your edits would appear in game. This was patched when Black Ops came out, then the few ways around it were patched as well. Haven't seen it since.

This is now patched and you can no longer do it. The only way of spoofing you name is on a jtag/rgh with the right tool and on xbls.

This will get you banned. I wouldn't do it.

Yea this was patched man, I did this and lost my FIRST ever xbox account .