Painted turtles can definitely freeze, I had an experience with it happening. We live in Akron Ohio and when I was around 16 we took a 2 week family vacation. I had a painted turtle (named Petey lol) that lived on our front porch in a tilted 20 gallon long half water half dry. I believe it was around March or April and while we were gone had unseasonably cold weather. Came home and he was completely submerged and all the water was frozen solid. We all thought he was obviously dead but I carefully chiseled him out and brought him inside as a frozen block of ice. Sat with him by the register vent while he thawed out. All of a sudden his tail popped out followed by his head and he was completely fine. Unsure how long he was completely frozen but amazing none the less.