I don't even know if ice is the problem. The key turns, but the mechanism won't... umm... I've lost the English word. Crap. It's as though the bolts aren't revolving properly, or something. However locking mechanisms work. It's not jammed, it just won't release. It's weird.

I will nonetheless try your suggestions. Can't hurt, after all, and maybe I'm totally wrong and it'll work. I still have to go out and buy stuff. Boo. :P