Canon T2i Shutter Release not happening

[remymerm]

Hey,

I have been using a Canon T2i for about 5 years now, saving up for the 7D Mark II...but anyway, For whatever reason when I am using the camera now, unless I am in one of the preset auto modes the shutter will not release unless I press the button 2 times, once to close and then once to release the shutter. This happens in the following modes: P, TV, AV, M, A-DEP. No matter what the setting (ISO, F, Flash blah blah) it stays like that. I have looked through all the settings and could not find anything that could fix it. I updated the firmware as well and restored the settings back to the factory defaults, and it did not fix the issue either. My friend who is a professional photographer looked at it as well and he could not figure it out, although he is not familiar with the rebel series. 

Any help would be appreciated, thanks!

[TCampbell]

Sounds like you have enabled "Mirror Lockup" mode.  In this mode you have to press the shutter button twice to take each exposure.  The first press causes the mirror to swing clear and lock in the "up" position.  The second press open the shutter and takes the shot.

This mode is sometimes used by photographers who want to ensure tha the vibration caused by the mirror swinging up doesn't affect the shot (it can cause a tiny vibration).  

It's a custom function setting.

[remymerm]

Sounds like that could be it but how do I get rid of it and turn it off? I never made any custom function settings. 

Thanks!