try some silicone spray lube on the weatherstripping seal around the port door and in the door latch mechanism.
I think I will try this. I have had some problems with frozen charge port door lately, and today's problem was especially vexing. First there was no sound when trying to open with the key. Fine, there usually isn't when there's a problem. There had not been a proper ice storm like there was a few days before, but there was still some ice visible in the gaps, so I took a plastic spatula to it. Nothing. Went to the owners manual, tried to try the suggestion there, but the diagram did not match what I saw. More spatula, and when I was done it was clear that everything had to be free of ice in the gaps - every side was coming up when pried (in the name of love, for all you U2 fans) - but still no click with the key and no opening. Some pounding on the door was mixed in here as well. Anyway, I gave up and hoped that the charge port door would "change its mind" after I drove the car. And it did. But when I looked for evidence of what the sticking culprit could have been, I found nothing. The one strange thing I noticed was that there was a very
thin coat of ice on the charge port door (that stopped short of the edges)... and nowhere else. Now why would that be? It was like that before I did anything.
This problem is quite a bad thing. Makes me think that there either should not be any latch/lock here (are there thieves in the night out to siphon electricity?) or that it should be something simple, external, and not delicate.