Specified in the camera and lens specifications 0c is the minimum temperature. That in itself is enough to void the warranty. You are operating the equipment out of its purpose design.
Thanks, I did leave it in my bag for several hours when I got back, so that it could warm up gradually. There is also nothing in the manual about low temperatures voiding the warranty, although it does mention that high temperatures could cause damage. I would therefore say, that even if they could find a way of determine what temperatures it was used in, they would have difficulty justifying not repairing under the warranty legally.Other issues are with cracked LCD screens.
Just note that it's extremely dangerous to Canon equipment to expose to temps below 0C. It also voids the warranty.
About the LCD screens. My experience is that the cold only makes them work "slower" especially those which are touchscreens. I've used outdoors at winter time different kind and sizes of LCD's over 15 years and never had any screen cracked from cold. Same about LCD's in my pocket or DSLR cameras over the years, no problems from cold weather.
And about the warranty issues if you use the Canon lenses in cold weather conditions. Here in Scandinavia it's expected that you use your equipment in very cold weather too. I haven't had any problems about the warranty when using my lenses in cold weather conditions.
Just week ago I got back my EF 70-200mm f/4 IS from Canon's service. The USM-motor was broken. And when I pick up the lens from the dealer I check all the functions of the lens in out side of the shop (it was -15'C then) before I accept the warranty repair of the lens. No problem with the dealer about my tests or warranty issues by the dealer nor Canon service. Even they know that I had used the lens in weather conditions from -30'C to +45'C. I get the normal 6 month warranty for the service work. So it extend my warranty because the original 2 year warranty was going to expire just after two weeks from the day I bring the lens for repair.
Of course I can tell only my experience's and maybe some countries it voids warranty.
If you take pictures in very cold weather it's a good idea to take a plastic bag with you. And before you go back inside the house put the gear in the plastic bag, close the bag and don't take the gear out of the bag until it's warmed up to room temperature. This is to prevent the formation of condensation on glass surfaces etc.
PS. Nice Aurora, thank's for sharing