Rebel t4i makes loud clicking sound, then won't turn on

[JimRebelt4i]

I have a Rebel t4i, and when turning it on, it makes a loud clicking sound for 5 seconds, then stops working. The clicking sound is from  the flash attempting to open (there's a lever under the flash). It moves rapidly for the five seconds, then stops. I've tried removing the battery, recharging, cleaning the contacts, etc. No luck. When swithing from single shot mode to video, the clicking/flash will occur again. I can use the camera to view images on the flash card, but the clicking noise persists and the camera is unusable. On vacation now, and desperate for a fix. 

[Skirball]

Maybe if you disable the flash then it won't try to open it?  Though I can't imagine that it tries to open the flash when you move to video...

If you try a manual mode (M, Av, Tv?) do you still get the clicking?

My next step would probably be to try to (gently) open the flash manually, but Canon will be by shortly to tell you that voids your warranty.

[TCampbell]

The only thing inside the camera body which physically moves or vibrates are

1)  The reflex mirror (which swings up and down)

2)  The flash release-catch

3)  The piezoelectric system which vibrates the low-pass filter to remote dust.

There are other moving parts in the lens of course.

The self-cleaning system (#3 on my list) may activate either at start up or at shut down.   It can also be manually activated through the menu system.  You might use the menu to tell the camera that you'd like it to perform a self-cleaning (on my camera the menu is labeled "Sensor Cleaning" with a sub-option to "Clean now" (your camera may not necessarily use the same labeling but it will have the feature.)  This would allow you to determine if this is the noise you are hearing.   This could be an indicator that your low-pass filter is not secured in the camera (this would require sending the camera in for service to repair.  Even though you can physically see the low-pass filter from the front of the body with the shutter open, the filter is installed through the back of the body and requires _substantial_ disassembly of the camera to reach it.)

Taking an exposure will cause the mirror to swing up and down.  You might set a slow shutter speed... say 2-5 seconds long so you can separate the sound of the swing-up from the sound of the swing-down to make sure your shutter isn't making funny noises.

You can manually push the button to release the catch on the flash and make sure that's working correctly.

ALSO... if you press the depth-of-field preveiw button (this is an unlabeled black button located on the front of the body near the lens mounting flange.  It is just below the the large button used to release the lock on the lens that you use when removing and switching lenses) this will cause the flash to pulse RAPIDLY for about a second.   When this happens, the flash WILL make a bit of a buzzing noises (it's certainly noisy enough to hear though not typically noisy enough to be disruptive.)  It provides you with enough light to see momentarily.  I'm wondering if this might be the buzzing noise that you hear as this would be completely normal.

[JimRebelt4i]

Time thanks for the reply. I've gotten the flash to deploy (open) and see what's happening. The latch that holds the flash in the closed position is moving back and forth very rapidly for five seconds. This is making the noise as described. So, with the flash already opened, I turn the camera 'on' and the lever/latch moves very quickly back and forth. I turn the camera off as soon as this happens as I don't want to ruin any components.

[TCampbell]

Well that's definitely not normal.  You'll want to call Canon service to ask them about that.