Yup, sounds like the problem. I had the same problem with mine.
I ran out of summer fluid earlier this month and I refilled it with some winter fluid. But I didnt use it right after refilling it. The next day it would not work at all. It took about 3 days of trying it for it to work because of the cold weather we were having. After a few days it warmed up enough for it to work and haven't had a problem since.
