In an attempt to fix another issue I am having with my 5DS-R, I dowloaded and installed the latest firmware from The Canon site. Something went wonky during that process and the camera was not responding correctly. So, I installed the latest firmware a second time which appears to have worked. However, now when I am shooting in LIVE mode the is no focus box any longer. What does show up when I move the joystick is the double line box that I can move around with the joystick and a message that says SWITCH TO AF L. I have no idea what that means or how to fix that or how to get back the focus box I used to have.
I tried to go back to the previous firmware however, I get a message saying that the previous firmware is older than the current firmware and it does not allow me to go back. Really?
The "L" is actually the nose of a face. That's the face-detection symbol/icon.
I would double-check your AF settings to ensure you're in the correct mode for what you want to do.
You can always reset your camera to go back to defect settings.
On firmware, no, you cannot revert to older versions. This is true of most if not all electronic equipment (cameras, cell phones, Blu-ray players, etc.)