My Canon EOS 650D (T4i) with 18-135 mm 1:3.5-5.6 IS STM lens, a few months old, sometimes does not shut down - approximately once in 500 switchings off. The camera continues to show on the LCD screen what was there before the shutting down attempt. In the picture, look at the position of the video-on-off switch and at the LCD screen - the screen should show nothing.
In this mode, camera does not respond to controls. The way around is to pull out the battery. And it looks like in this mode the battery power is consumed at a high rate.
Does anybody know whether a firmware update is coming? There is none on Canon's web site.