What I mean by that is, if they switched it on after that part had frozen then fuck all would thaw it, isn't the idea of u/s heating to prevent frost from forming, not for melting it. That's why I was questioning which area it was, it had been -7 on Tuesday overnight, that ground would have been solid until the weekend.
I'm not making excuses, just looking at it logically. I'm just as disgusted the game was off as everyone else, but the fact is something caused the ground at that part to be brick hard and the fact it gets no sunlight and the temperature has been so severe this past week, it's the most likely explanation.