Sorry to hear that your EOS Rebel T3i won't turn on.
Please try removing the battery and charging it to its full capacity. You may also try using an alternate battery. To ensure the battery has a good connection with the camera, clean the contacts on the battery with a soft microfiber cleaning cloth. When this is done, put the battery back in the camera and turn the camera on. If the camera does not turn on, your EOS Rebel T3i will require service.
To start your repair process, you'll need to complete a Repair Request on our website.
If this is a time sensitive-matter, additional support options are available at Contact Us.
Thank you. I will try this, however, the problem is not that the camera will not turn on. The"main dial", as it is referred to in the manual used to change the fstop and shutter speed, immediately behind the shutter button that will not rotate either left or right. It seems to be locked or stuck. Any ideas about this?
There's really no reason for the Main Dial to be stuck. There's no locking function.
Regrettably, your camera will require service to correct this issue. You may set the repair of your camera here.
I wonder if it ever worked because I haven't had the camera that long and always used it on auto until recently. Unfortunately it is too late now as it is no longer under warranty. I will have to check into getting it repaired. Fortunately I discovered that the Q button also allows me to change shutter speeds and F stops. Thank you.