Use a hot key (lighter in my pocket at all times at the moment) to get into it if stuck, takes about 3/4 heatings to get in.
You then want to spray deicer into the lock or methanol - never use water, you've just created a bigger ice cube!
You will also find that the push buttom goes in and stays in, if it doesn't come back out it will just bounce open again because it's in opening position. You can quickly wave the lighter about under the button to melt the ice, I also give under the lock barrel a 2second heat to help thaw it out.
Once moving freely get the deicer or similar in there, something to displace the water that won't freeze.
I find a "tuned" lighter is ideal; lift metal cover off, push gas valve up off wheel, move to the side then push back down, move valve round and try that, 2 inch flame!